diff --git a/src/builtins/arrays.rs b/src/builtins/arrays.rs
index 781a2f2..4984a89 100644
--- a/src/builtins/arrays.rs
+++ b/src/builtins/arrays.rs
@@ -3,7 +3,7 @@
 
 use crate::ast::Expr;
 use crate::builtins;
-use crate::builtins::utils::{ensure_args_count, ensure_array};
+use crate::builtins::utils::{ensure_args_count, ensure_array, ensure_numeric};
 use crate::lexer::Span;
 use crate::value::Value;
 
@@ -15,6 +15,7 @@ use std::rc::Rc;
 pub fn register(m: &mut HashMap<&'static str, builtins::BuiltinFcn>) {
     m.insert("array.concat", concat);
     m.insert("array.reverse", reverse);
+    m.insert("array.slice", slice);
 }
 
 fn concat(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
@@ -29,13 +30,36 @@ fn concat(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
 
 fn reverse(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
     let name = "array.reverse";
-    ensure_args_count(span, name, params, args, 2)?;
+    ensure_args_count(span, name, params, args, 1)?;
 
     let mut v1 = ensure_array(name, &params[0], args[0].clone())?;
     Rc::make_mut(&mut v1).reverse();
     Ok(Value::Array(v1))
 }
 
-/*
 fn slice(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
-*/
+    let name = "array.slice";
+    ensure_args_count(span, name, params, args, 3)?;
+
+    let array = ensure_array(name, &params[0], args[0].clone())?;
+    let start = ensure_numeric(name, &params[1], &args[1].clone())?;
+    let stop = ensure_numeric(name, &params[2], &args[2].clone())?;
+
+    if start != start.floor() || stop != stop.floor() {
+        return Ok(Value::Undefined);
+    }
+
+    // TODO: usize conversion checks.
+    let start = start as usize;
+    let stop = match stop as usize {
+        s if s > array.len() => array.len(),
+        s => s,
+    };
+
+    if start >= stop {
+        return Ok(Value::new_array());
+    }
+
+    let slice = &array[start..stop];
+    Ok(Value::from_array(slice.to_vec()))
+}
diff --git a/tests/interpreter/cases/builtins/arrays/concat.yaml b/tests/interpreter/cases/builtins/arrays/concat.yaml
new file mode 100644
index 0000000..1888f86
--- /dev/null
+++ b/tests/interpreter/cases/builtins/arrays/concat.yaml
@@ -0,0 +1,63 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+cases:
+  - note: all
+    data: {}
+    modules:
+      - |
+        package test
+
+        x = [
+          array.concat([1, 2, 3], [4, 5, 6]),
+          array.concat([], [1]),
+          array.concat([1], []),
+          array.concat([], []),
+        ]
+        # Undefined
+        r { false }
+        u1 = array.concat([1], r)
+        u2 = array.concat(r, r)
+    query: data.test
+    want_result:
+      x :
+        - [1, 2, 3, 4, 5, 6]
+        - [1]
+        - [1]
+        - []
+
+  - note: concat-invalid-arg1
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.concat(1, [2])
+    query: data.test
+    error: "`array.concat` expects array argument."
+
+  - note: concat-invalid-arg2
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.concat([2], 1)
+    query: data.test
+    error: "`array.concat` expects array argument."
+
+  - note: concat-less-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.concat([2])
+    query: data.test
+    error: "`array.concat` expects 2 arguments"
+
+  - note: concat-more-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.concat([2], [3], [4])
+    query: data.test
+    error: "`array.concat` expects 2 arguments"
diff --git a/tests/interpreter/cases/builtins/arrays/reverse.yaml b/tests/interpreter/cases/builtins/arrays/reverse.yaml
new file mode 100644
index 0000000..98be4df
--- /dev/null
+++ b/tests/interpreter/cases/builtins/arrays/reverse.yaml
@@ -0,0 +1,51 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+cases:
+  - note: all
+    data: {}
+    modules:
+      - |
+        package test
+        y = [
+          array.reverse([1, 2, 3]),
+          array.reverse([]),
+          array.reverse(array.reverse([1, 2, 3])),
+        ]
+
+        # Undefined
+        r { false }
+        u3 = array.reverse(r)
+    query: data.test
+    want_result:
+      y :
+        - [3, 2,1]
+        - []
+        - [1, 2, 3]
+
+  - note: reverse-invalid-arg
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.reverse(1)
+    query: data.test
+    error: "`array.reverse` expects array argument."
+
+  - note: reverse-less-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.reverse()
+    query: data.test
+    error: "at least one argument required for function calls"
+
+  - note: reverse-more-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.reverse([2], [3])
+    query: data.test
+    error: "`array.reverse` expects 1 argument"
diff --git a/tests/interpreter/cases/builtins/arrays/slice.yaml b/tests/interpreter/cases/builtins/arrays/slice.yaml
new file mode 100644
index 0000000..481a025
--- /dev/null
+++ b/tests/interpreter/cases/builtins/arrays/slice.yaml
@@ -0,0 +1,86 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+cases:
+  - note: all
+    data: {}
+    modules:
+      - |
+        package test
+
+        z = [
+           array.slice([1, 2, 3], 0, 1),
+           array.slice([1, 2, 3], 0, 2),
+           array.slice([1, 2, 3], 2, 3),
+           array.slice([1, 2, 3], 0, 5),
+           array.slice([1, 2, 3], 5, 5),
+           array.slice([1, 2, 3], -5, 5),
+           array.slice([1, 2, 3], -5, 0),
+           array.slice([1, 2, 3], -5, 1),
+           array.slice([], -5, 1),
+        ]        
+
+        # Undefined
+        r { false }
+        u1 = array.slice(r, 1, 2)
+        u2 = array.slice([1], r, 2)
+        u3 = array.slice([1], 1, r)
+        u4 = array.slice([5], 1.1, 2)
+        u5 = array.slice([5], 1, 2.1)        
+    query: data.test
+    want_result:
+      z :
+        - [1]
+        - [1, 2]
+        - [3]
+        - [1, 2, 3]
+        - []
+        - [1, 2, 3]
+        - []
+        - [1]
+        - []
+
+  - note: invalid-arg1
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.slice(1, 2, 3)
+    query: data.test
+    error: "`array.slice` expects array argument."
+
+  - note: invalid-arg2
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.slice([2], "1", 2)
+    query: data.test
+    error: "`array.slice` expects numeric argument."
+
+  - note: invalid-arg3
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.slice([2], 1,  "2")
+    query: data.test
+    error: "`array.slice` expects numeric argument."
+
+  - note: less-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.slice([2], 1)
+    query: data.test
+    error: "`array.slice` expects 3 arguments"
+
+  - note: more-args
+    data: {}
+    modules:
+      - |
+        package test
+        x = array.slice([2], 1, 2, 3)
+    query: data.test
+    error: "`array.slice` expects 3 arguments"