diff --git a/config.json b/config.json
index 6e57918..f7e46de 100644
--- a/config.json
+++ b/config.json
@@ -348,6 +348,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 3
+      },
+      {
+        "slug": "flatten-array",
+        "name": "Flatten Array",
+        "uuid": "ddf5e66f-73c6-4fcf-9ed9-dde95d896d4a",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
       }
     ]
   },
diff --git a/exercises/practice/flatten-array/.docs/instructions.md b/exercises/practice/flatten-array/.docs/instructions.md
new file mode 100644
index 0000000..89dacfa
--- /dev/null
+++ b/exercises/practice/flatten-array/.docs/instructions.md
@@ -0,0 +1,11 @@
+# Instructions
+
+Take a nested list and return a single flattened list with all values except nil/null.
+
+The challenge is to take an arbitrarily-deep nested list-like structure and produce a flattened structure without any nil/null values.
+
+For example:
+
+input: [1,[2,3,null,4],[null],5]
+
+output: [1,2,3,4,5]
diff --git a/exercises/practice/flatten-array/.meta/config.json b/exercises/practice/flatten-array/.meta/config.json
new file mode 100644
index 0000000..961effd
--- /dev/null
+++ b/exercises/practice/flatten-array/.meta/config.json
@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "flatten-array.8th"
+    ],
+    "test": [
+      "test.8th"
+    ],
+    "example": [
+      ".meta/example.8th"
+    ]
+  },
+  "blurb": "Take a nested list and return a single list with all values except nil/null.",
+  "source": "Interview Question",
+  "source_url": "https://reference.wolfram.com/language/ref/Flatten.html"
+}
diff --git a/exercises/practice/flatten-array/.meta/example.8th b/exercises/practice/flatten-array/.meta/example.8th
new file mode 100644
index 0000000..79eff9f
--- /dev/null
+++ b/exercises/practice/flatten-array/.meta/example.8th
@@ -0,0 +1,4 @@
+: flatten \ a -- a
+  array? if ( flatten a:+ ) a:new a:reduce ;then
+  null? if drop [] else a:new swap a:push then  
+;
diff --git a/exercises/practice/flatten-array/.meta/tests.toml b/exercises/practice/flatten-array/.meta/tests.toml
new file mode 100644
index 0000000..6300219
--- /dev/null
+++ b/exercises/practice/flatten-array/.meta/tests.toml
@@ -0,0 +1,43 @@
+# 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.
+
+[8c71dabd-da60-422d-a290-4a571471fb14]
+description = "empty"
+
+[d268b919-963c-442d-9f07-82b93f1b518c]
+description = "no nesting"
+
+[3f15bede-c856-479e-bb71-1684b20c6a30]
+description = "flattens a nested array"
+
+[c84440cc-bb3a-48a6-862c-94cf23f2815d]
+description = "flattens array with just integers present"
+
+[d3d99d39-6be5-44f5-a31d-6037d92ba34f]
+description = "5 level nesting"
+
+[d572bdba-c127-43ed-bdcd-6222ac83d9f7]
+description = "6 level nesting"
+
+[0705a8e5-dc86-4cec-8909-150c5e54fa9c]
+description = "null values are omitted from the final result"
+
+[c6cf26de-8ccd-4410-84bd-b9efd88fd2bc]
+description = "consecutive null values at the front of the list are omitted from the final result"
+
+[382c5242-587e-4577-b8ce-a5fb51e385a1]
+description = "consecutive null values in the middle of the list are omitted from the final result"
+
+[ef1d4790-1b1e-4939-a179-51ace0829dbd]
+description = "6 level nest list with null values"
+
+[85721643-705a-4150-93ab-7ae398e2942d]
+description = "all values in nested list are null"
diff --git a/exercises/practice/flatten-array/flatten-array.8th b/exercises/practice/flatten-array/flatten-array.8th
new file mode 100644
index 0000000..db0eda1
--- /dev/null
+++ b/exercises/practice/flatten-array/flatten-array.8th
@@ -0,0 +1,3 @@
+: flatten \ a -- a
+
+;
diff --git a/exercises/practice/flatten-array/libs/exercism/test b/exercises/practice/flatten-array/libs/exercism/test
new file mode 100644
index 0000000..77a05f3
--- /dev/null
+++ b/exercises/practice/flatten-array/libs/exercism/test
@@ -0,0 +1,162 @@
+needs console/loaded
+
+\ -----------------------------------------------------------------
+
+ns: test
+
+-1 var, test-count
+var tests-passed
+var tests-failed
+var tests-skipped
+true var, run-test
+
+\ Some utility words
+
+: array-insens-dot \ x --  \\ removes leading space on stringified arrays
+  dup >kind ns:a n:= 
+  if 
+    >s s:trim 
+  then 
+  .
+;
+
+: test-passed \ s x x --   \\ test name, expected value, actual value
+    2drop
+    1 tests-passed n:+!
+    con:green con:onBlack . space " ... OK" . con:white con:onBlack cr
+;
+
+: test-skipped \ s --
+    1 tests-skipped n:+!
+    con:cyan con:onBlack . space " ... SKIPPED" . con:white con:onBlack cr
+;
+
+: test-failed \ s x x --   \\ test name, expected value, actual value
+    1 tests-failed n:+!
+    rot
+    con:red con:onBlack . space " ... FAIL" . con:white con:onBlack cr
+    "    Actual:    «" . array-insens-dot "»" . cr
+    "    Expected:  «" . array-insens-dot "»" . cr cr
+;
+
+: isword?  \ x -- x f
+   dup  >kind  ns:w   n:= 
+;
+
+: run-test? \ -- T
+   run-test @ if true else "RUN_ALL_TESTS" getenv n:>bool then
+;
+
+\ Num passed + num skipped + num failed should == num tests
+: all-tests-run? \ -- T
+    tests-passed @ tests-skipped @ tests-failed @ n:+ n:+
+    test-count @ n:=
+;
+
+\ returns true if x is a date, false otherwise
+: date? \ x -- x T
+    dup >kind ns:d n:=
+;
+
+\ adapted from 8th forum -- https://8th-dev.com/forum/index.php/topic,2745.0.html
+: eq? \ x x -- T
+   \ are the items the same kind?
+   2dup >kind swap >kind n:=
+   !if 2drop false ;then
+
+   \ same kind: try different comparators
+   number? if n:= ;then
+   string? if s:= ;then
+   array?  if ' eq? a:= 2nip ;then
+   map?    if ' eq? m:= 2nip ;then
+   date?   if d:= ;then
+
+   \ otherwise fall back to 'lazy evaluation'
+   l: =
+;
+
+: check-depth \ ... n -- ...
+  dup>r
+  n:1+ depth n:=
+  !if
+    con:red con:onBlack 
+    "PANIC: expected stack depth to be " . r> . cr
+    "Stack is:" . cr
+    .s cr
+    255 die
+  then
+  rdrop
+;
+
+\ -----------------------------------------------------------------
+
+\ status report at end of run
+( all-tests-run?  
+  !if con:red con:onBlack "... FAIL - not all tests completed" . con:white con:onBlack cr then
+) onexit
+
+\ Print a summary of the tests run
+( con:white con:onBlack
+  test-count   @ . space "tests planned - " .
+  tests-passed @ . space "passed - " .
+  tests-skipped @ . space "skipped - " .
+  tests-failed @ . space "failed" . cr
+) onexit
+
+\ -----------------------------------------------------------------
+\ The public-facing words
+\ -----------------------------------------------------------------
+    
+: equal? \ s x w -- | s w x --
+   run-test? !if 2drop test-skipped ;; then
+   isword? !if swap then
+   w:exec
+   3 check-depth
+   2dup             \ so test-failed can show actual and expected
+   eq? if test-passed else test-failed then
+;
+
+: true? \ s w --
+   run-test? !if drop test-skipped ;; then
+   w:exec
+   2 check-depth
+   true swap dup    \ so test-failed can show actual and expected
+   if test-passed else test-failed then 
+;
+
+: false? \ s w --
+   run-test? !if drop test-skipped ;; then
+   w:exec
+   2 check-depth
+   false swap dup    \ so test-failed can show actual and expected
+   !if test-passed else test-failed then 
+;
+
+: null? \ s w --
+   run-test? !if drop test-skipped ;; then
+   w:exec
+   2 check-depth
+   null swap dup     \ so test-failed can show actual and expected
+   G:null? nip if test-passed else test-failed then 
+;
+
+: SKIP-REST-OF-TESTS false run-test ! ;
+
+: tests \ n -- 
+    test-count ! 
+;
+
+\ Set the exit status:
+\   0 = all OK
+\   1 = not all tests were run (some error occurred)
+\   2 = some tests failed
+: end-of-tests \ --
+    all-tests-run?
+    if
+      tests-failed @ 0 n:= if 0 else 2 then
+    else
+      1
+    then
+    die
+;
+
diff --git a/exercises/practice/flatten-array/test.8th b/exercises/practice/flatten-array/test.8th
new file mode 100644
index 0000000..55df3d9
--- /dev/null
+++ b/exercises/practice/flatten-array/test.8th
@@ -0,0 +1,64 @@
+"flatten-array.8th" f:include
+needs exercism/test
+with: test
+11 tests
+
+"empty"
+    ( [] flatten )
+    []
+    equal?
+
+SKIP-REST-OF-TESTS
+
+"no nesting"
+    ( [0, 1, 2] flatten )
+    [0, 1, 2]
+    equal?
+
+"flattens a nested array"
+    ( [[[]]] flatten )
+    []
+    equal?
+
+"flattens array with just integers present"
+    ( [1, [2, 3, 4, 5, 6, 7], 8] flatten )
+    [1, 2, 3, 4, 5, 6, 7, 8]
+    equal?
+
+"5 level nesting"
+    ( [0, 2, [[2, 3], 8, 100, 4, [[[50]]]], -2] flatten )
+    [0, 2, 2, 3, 8, 100, 4, 50, -2]
+    equal?
+
+"6 level nesting"
+    ( [1, [2, [[3]], [4, [[5]]], 6, 7], 8] flatten )
+    [1, 2, 3, 4, 5, 6, 7, 8]
+    equal?
+
+"null values are omitted from the final result"
+    ( [1, 2, null] flatten )
+    [1, 2]
+    equal?
+
+"consecutive null values at the front of the list are omitted from the final result"
+    ( [null, null, 3] flatten )
+    [3]
+    equal?
+
+"consecutive null values in the middle of the list are omitted from the final result"
+    ( [1, null, null, 4] flatten )
+    [1, 4]
+    equal?
+
+"6 level nest list with null values"
+    ( [0, 2, [[2, 3], 8, [[100]], null, [[null]]], -2] flatten )
+    [0, 2, 2, 3, 8, 100, -2]
+    equal?
+
+"all values in nested list are null"
+    ( [null, [[[null]]], null, null, [[null, null], null], null] flatten )
+    []
+    equal?
+
+end-of-tests
+;with