diff --git a/config.json b/config.json
index d27bbf7..8fac868 100644
--- a/config.json
+++ b/config.json
@@ -641,6 +641,14 @@
           "text_formatting"
         ]
       },
+      {
+        "slug": "custom-set",
+        "name": "Custom Set",
+        "uuid": "560b738f-c20d-43ac-9bc5-4821628adc00",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "kindergarten-garden",
         "name": "Kindergarten Garden",
diff --git a/exercises/practice/custom-set/.docs/instructions.md b/exercises/practice/custom-set/.docs/instructions.md
new file mode 100644
index 0000000..33b90e2
--- /dev/null
+++ b/exercises/practice/custom-set/.docs/instructions.md
@@ -0,0 +1,7 @@
+# Instructions
+
+Create a custom set type.
+
+Sometimes it is necessary to define a custom data structure of some type, like a set.
+In this exercise you will define your own set.
+How it works internally doesn't matter, as long as it behaves like a set of unique elements.
diff --git a/exercises/practice/custom-set/.meta/config.json b/exercises/practice/custom-set/.meta/config.json
new file mode 100644
index 0000000..5b76111
--- /dev/null
+++ b/exercises/practice/custom-set/.meta/config.json
@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "custom-set.coffee"
+    ],
+    "test": [
+      "custom-set.spec.coffee"
+    ],
+    "example": [
+      ".meta/example.coffee"
+    ]
+  },
+  "blurb": "Create a custom set type."
+}
diff --git a/exercises/practice/custom-set/.meta/example.coffee b/exercises/practice/custom-set/.meta/example.coffee
new file mode 100644
index 0000000..8286fa5
--- /dev/null
+++ b/exercises/practice/custom-set/.meta/example.coffee
@@ -0,0 +1,42 @@
+class CustomSet
+  constructor: (values) ->
+    values.sort()
+    @values = values.filter (value, index) ->
+      values.indexOf(value) is index
+
+  empty: ->
+    @values.length == 0
+
+  contains: (value) ->
+    @values.indexOf(value) != -1
+
+  subset: (other) ->
+    @values.every (item) -> other.contains item
+
+  disjoint: (other) ->
+    @values.every (item) -> !other.contains item
+
+  equal: (other) ->
+    if @values.length != other.values.length
+      return false
+    else
+
+    for elt, i in @values
+        return false if elt != other.values[i]
+    true
+
+  add: (value) ->
+    if !(@contains value)
+      @values.push value
+      @values.sort()
+
+  intersection: (other) ->
+    new CustomSet @values.filter (item) -> other.contains item
+
+  difference: (other) ->
+    new CustomSet @values.filter (item) -> !other.contains item
+  
+  union: (other) ->
+    new CustomSet @values.concat other.values
+
+module.exports = CustomSet
diff --git a/exercises/practice/custom-set/.meta/tests.toml b/exercises/practice/custom-set/.meta/tests.toml
new file mode 100644
index 0000000..430c139
--- /dev/null
+++ b/exercises/practice/custom-set/.meta/tests.toml
@@ -0,0 +1,130 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[20c5f855-f83a-44a7-abdd-fe75c6cf022b]
+description = "Returns true if the set contains no elements -> sets with no elements are empty"
+
+[d506485d-5706-40db-b7d8-5ceb5acf88d2]
+description = "Returns true if the set contains no elements -> sets with elements are not empty"
+
+[759b9740-3417-44c3-8ca3-262b3c281043]
+description = "Sets can report if they contain an element -> nothing is contained in an empty set"
+
+[f83cd2d1-2a85-41bc-b6be-80adbff4be49]
+description = "Sets can report if they contain an element -> when the element is in the set"
+
+[93423fc0-44d0-4bc0-a2ac-376de8d7af34]
+description = "Sets can report if they contain an element -> when the element is not in the set"
+
+[c392923a-637b-4495-b28e-34742cd6157a]
+description = "A set is a subset if all of its elements are contained in the other set -> empty set is a subset of another empty set"
+
+[5635b113-be8c-4c6f-b9a9-23c485193917]
+description = "A set is a subset if all of its elements are contained in the other set -> empty set is a subset of non-empty set"
+
+[832eda58-6d6e-44e2-92c2-be8cf0173cee]
+description = "A set is a subset if all of its elements are contained in the other set -> non-empty set is not a subset of empty set"
+
+[c830c578-8f97-4036-b082-89feda876131]
+description = "A set is a subset if all of its elements are contained in the other set -> set is a subset of set with exact same elements"
+
+[476a4a1c-0fd1-430f-aa65-5b70cbc810c5]
+description = "A set is a subset if all of its elements are contained in the other set -> set is a subset of larger set with same elements"
+
+[d2498999-3e46-48e4-9660-1e20c3329d3d]
+description = "A set is a subset if all of its elements are contained in the other set -> set is not a subset of set that does not contain its elements"
+
+[7d38155e-f472-4a7e-9ad8-5c1f8f95e4cc]
+description = "Sets are disjoint if they share no elements -> the empty set is disjoint with itself"
+
+[7a2b3938-64b6-4b32-901a-fe16891998a6]
+description = "Sets are disjoint if they share no elements -> empty set is disjoint with non-empty set"
+
+[589574a0-8b48-48ea-88b0-b652c5fe476f]
+description = "Sets are disjoint if they share no elements -> non-empty set is disjoint with empty set"
+
+[febeaf4f-f180-4499-91fa-59165955a523]
+description = "Sets are disjoint if they share no elements -> sets are not disjoint if they share an element"
+
+[0de20d2f-c952-468a-88c8-5e056740f020]
+description = "Sets are disjoint if they share no elements -> sets are disjoint if they share no elements"
+
+[4bd24adb-45da-4320-9ff6-38c044e9dff8]
+description = "Sets with the same elements are equal -> empty sets are equal"
+
+[f65c0a0e-6632-4b2d-b82c-b7c6da2ec224]
+description = "Sets with the same elements are equal -> empty set is not equal to non-empty set"
+
+[81e53307-7683-4b1e-a30c-7e49155fe3ca]
+description = "Sets with the same elements are equal -> non-empty set is not equal to empty set"
+
+[d57c5d7c-a7f3-48cc-a162-6b488c0fbbd0]
+description = "Sets with the same elements are equal -> sets with the same elements are equal"
+
+[dd61bafc-6653-42cc-961a-ab071ee0ee85]
+description = "Sets with the same elements are equal -> sets with different elements are not equal"
+
+[06059caf-9bf4-425e-aaff-88966cb3ea14]
+description = "Sets with the same elements are equal -> set is not equal to larger set with same elements"
+
+[d4a1142f-09aa-4df9-8b83-4437dcf7ec24]
+description = "Sets with the same elements are equal -> set is equal to a set constructed from an array with duplicates"
+
+[8a677c3c-a658-4d39-bb88-5b5b1a9659f4]
+description = "Unique elements can be added to a set -> add to empty set"
+
+[0903dd45-904d-4cf2-bddd-0905e1a8d125]
+description = "Unique elements can be added to a set -> add to non-empty set"
+
+[b0eb7bb7-5e5d-4733-b582-af771476cb99]
+description = "Unique elements can be added to a set -> adding an existing element does not change the set"
+
+[893d5333-33b8-4151-a3d4-8f273358208a]
+description = "Intersection returns a set of all shared elements -> intersection of two empty sets is an empty set"
+
+[d739940e-def2-41ab-a7bb-aaf60f7d782c]
+description = "Intersection returns a set of all shared elements -> intersection of an empty set and non-empty set is an empty set"
+
+[3607d9d8-c895-4d6f-ac16-a14956e0a4b7]
+description = "Intersection returns a set of all shared elements -> intersection of a non-empty set and an empty set is an empty set"
+
+[b5120abf-5b5e-41ab-aede-4de2ad85c34e]
+description = "Intersection returns a set of all shared elements -> intersection of two sets with no shared elements is an empty set"
+
+[af21ca1b-fac9-499c-81c0-92a591653d49]
+description = "Intersection returns a set of all shared elements -> intersection of two sets with shared elements is a set of the shared elements"
+
+[c5e6e2e4-50e9-4bc2-b89f-c518f015b57e]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference of two empty sets is an empty set"
+
+[2024cc92-5c26-44ed-aafd-e6ca27d6fcd2]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference of empty set and non-empty set is an empty set"
+
+[e79edee7-08aa-4c19-9382-f6820974b43e]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference of a non-empty set and an empty set is the non-empty set"
+
+[c5ac673e-d707-4db5-8d69-7082c3a5437e]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference of two non-empty sets is a set of elements that are only in the first set"
+
+[20d0a38f-7bb7-4c4a-ac15-90c7392ecf2b]
+description = "Difference (or Complement) of a set is a set of all elements that are only in the first set -> difference removes all duplicates in the first set"
+
+[c45aed16-5494-455a-9033-5d4c93589dc6]
+description = "Union returns a set of all elements in either set -> union of empty sets is an empty set"
+
+[9d258545-33c2-4fcb-a340-9f8aa69e7a41]
+description = "Union returns a set of all elements in either set -> union of an empty set and non-empty set is the non-empty set"
+
+[3aade50c-80c7-4db8-853d-75bac5818b83]
+description = "Union returns a set of all elements in either set -> union of a non-empty set and empty set is the non-empty set"
+
+[a00bb91f-c4b4-4844-8f77-c73e2e9df77c]
+description = "Union returns a set of all elements in either set -> union of non-empty sets contains all unique elements"
diff --git a/exercises/practice/custom-set/custom-set.coffee b/exercises/practice/custom-set/custom-set.coffee
new file mode 100644
index 0000000..c0c1d5b
--- /dev/null
+++ b/exercises/practice/custom-set/custom-set.coffee
@@ -0,0 +1,22 @@
+class CustomSet
+  constructor: (values) ->
+
+  empty: ->
+
+  contains: (value) ->
+
+  subset: (other) ->
+
+  disjoint: (other) ->
+
+  equall: (other) ->
+
+  add: (value) ->
+
+  intersection: (other) ->
+
+  difference: (other) ->
+
+  union: (other) ->
+
+module.exports = CustomSet
diff --git a/exercises/practice/custom-set/custom-set.spec.coffee b/exercises/practice/custom-set/custom-set.spec.coffee
new file mode 100644
index 0000000..b786c11
--- /dev/null
+++ b/exercises/practice/custom-set/custom-set.spec.coffee
@@ -0,0 +1,206 @@
+CustomSet = require './custom-set'
+
+describe 'Custom Set', ->
+  describe 'Empty', ->
+    it 'sets with no elements are empty', ->
+      set = new CustomSet []
+      expect(set.empty()).toEqual true
+
+    xit 'sets with elements are not empty', ->
+      set = new CustomSet [1]
+      expect(set.empty()).toEqual false
+
+  describe 'Contains', ->
+    xit 'nothing is contained in an empty set', ->
+      set = new CustomSet []
+      expect(set.contains 1).toEqual false
+
+    xit 'when the element is in the set', ->
+      set = new CustomSet [1, 2, 3]
+      expect(set.contains 1).toEqual true
+
+    xit 'when the element is not in the set', ->
+      set = new CustomSet [1, 2, 3]
+      expect(set.contains 4).toEqual false
+
+  describe 'Subset', ->
+    xit 'empty set is a subset of another empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.subset set2).toEqual true
+
+    xit 'empty set is a subset of non-empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [1]
+      expect(set1.subset set2).toEqual true
+
+    xit 'non-empty set is not a subset of empty set', ->
+      set1 = new CustomSet [1]
+      set2 = new CustomSet []
+      expect(set1.subset set2).toEqual false
+
+    xit 'set is a subset of set with exact same elements', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [1, 2, 3]
+      expect(set1.subset set2).toEqual true
+
+    xit 'set is a subset of larger set with same elements', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [4, 1, 2, 3]
+      expect(set1.subset set2).toEqual true
+
+    xit 'set is not a subset of set that does not contain its elements', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [4, 1, 3]
+      expect(set1.subset set2).toEqual false
+
+  describe 'Disjoint', ->
+    xit 'the empty set is disjoint with itself', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.disjoint set2).toEqual true
+
+    xit 'empty set is disjoint with non-empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [1]
+      expect(set1.disjoint set2).toEqual true
+
+    xit 'non-empty set is disjoint with empty set', ->
+      set1 = new CustomSet [1]
+      set2 = new CustomSet []
+      expect(set1.disjoint set2).toEqual true
+
+    xit 'sets are not disjoint if they share an element', ->
+      set1 = new CustomSet [1, 2]
+      set2 = new CustomSet [2, 3]
+      expect(set1.disjoint set2).toEqual false
+
+    xit 'sets are disjoint if they share no elements', ->
+      set1 = new CustomSet [1, 2]
+      set2 = new CustomSet [3, 4]
+      expect(set1.disjoint set2).toEqual true
+
+  describe 'Equal', ->
+    xit 'empty sets are equal', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.equal set2).toEqual true
+
+    xit 'empty set is not equal to non-empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [1, 2, 3]
+      expect(set1.equal set2).toEqual false
+
+    xit 'non-empty set is not equal to empty set', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet []
+      expect(set1.equal set2).toEqual false
+
+    xit 'sets with the same elements are equal', ->
+      set1 = new CustomSet [1, 2]
+      set2 = new CustomSet [2, 1]
+      expect(set1.equal set2).toEqual true
+
+    xit 'sets with different elements are not equal', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [1, 2, 4]
+      expect(set1.equal set2).toEqual false
+
+    xit 'set is not equal to larger set with same elements', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [1, 2, 3, 4]
+      expect(set1.equal set2).toEqual false
+
+    xit 'set is equal to a set constructed from an array with duplicates', ->
+      set1 = new CustomSet [1]
+      set2 = new CustomSet [1, 1]
+      expect(set1.equal set2).toEqual true
+
+  describe 'Add', ->
+    xit 'add to empty set', ->
+      set = new CustomSet []
+      set.add 3
+      expect(set.values).toEqual [3]
+
+    xit 'add to non-empty set', ->
+      set = new CustomSet [1, 2, 4]
+      set.add 3
+      expect(set.values).toEqual [1, 2, 3, 4]
+
+    xit 'adding an existing element does not change the set', ->
+      set = new CustomSet [1, 2, 3]
+      set.add 3
+      expect(set.values).toEqual [1, 2, 3]
+
+  describe 'Intersection', ->
+    xit 'intersection of two empty sets is an empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.intersection set2).toEqual new CustomSet []
+
+    xit 'intersection of an empty set and non-empty set is an empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [3, 2, 5]
+      expect(set1.intersection set2).toEqual new CustomSet []
+
+    xit 'intersection of a non-empty set and an empty set is an empty set', ->
+      set1 = new CustomSet [1, 2, 3, 4]
+      set2 = new CustomSet []
+      expect(set1.intersection set2).toEqual new CustomSet []
+
+    xit 'intersection of two sets with no shared elements is an empty set', ->
+      set1 = new CustomSet [1, 2, 3]
+      set2 = new CustomSet [4, 5, 6]
+      expect(set1.intersection set2).toEqual new CustomSet []
+
+    xit 'intersection of two sets with shared elements is a set of the shared elements', ->
+      set1 = new CustomSet [1, 2, 3, 4]
+      set2 = new CustomSet [3, 2, 5]
+      expect(set1.intersection set2).toEqual new CustomSet [2, 3]
+
+  describe 'Difference', ->
+    xit 'difference of two empty sets is an empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.difference set2).toEqual new CustomSet []
+
+    xit 'difference of empty set and non-empty set is an empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [3, 2, 5]
+      expect(set1.difference set2).toEqual new CustomSet []
+
+    xit 'difference of a non-empty set and an empty set is the non-empty set', ->
+      set1 = new CustomSet [1, 2, 3, 4]
+      set2 = new CustomSet []
+      expect(set1.difference set2).toEqual new CustomSet [1, 2, 3, 4]
+
+    xit 'difference of two non-empty sets is a set of elements that are only in the first set', ->
+      set1 = new CustomSet [3, 2, 1]
+      set2 = new CustomSet [2, 4]
+      expect(set1.difference set2).toEqual new CustomSet [1, 3]
+
+    xit 'difference removes all duplicates in the first set', ->
+      set1 = new CustomSet [1, 1]
+      set2 = new CustomSet [1]
+      expect(set1.difference set2).toEqual new CustomSet []
+
+  describe 'Union', ->
+    xit 'union of empty sets is an empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet []
+      expect(set1.union set2).toEqual new CustomSet []
+
+    xit 'union of an empty set and non-empty set is the non-empty set', ->
+      set1 = new CustomSet []
+      set2 = new CustomSet [2]
+      expect(set1.union set2).toEqual new CustomSet [2]
+
+    xit 'union of a non-empty set and empty set is the non-empty set', ->
+      set1 = new CustomSet [1, 3]
+      set2 = new CustomSet []
+      expect(set1.union set2).toEqual new CustomSet [1, 3]
+
+    xit 'union of non-empty sets contains all unique elements', ->
+      set1 = new CustomSet [1, 3]
+      set2 = new CustomSet [2, 3]
+      expect(set1.union set2).toEqual new CustomSet [3, 2, 1]