diff --git a/src/OrderedList.php b/src/OrderedList.php
index 4a2ad0d..7ae737a 100644
--- a/src/OrderedList.php
+++ b/src/OrderedList.php
@@ -5,10 +5,13 @@
 
 use Webmozart\Assert\Assert;
 use function array_combine;
+use function array_fill;
 use function array_keys;
 use function array_map;
 use function array_merge;
+use function array_replace;
 use function array_values;
+use function is_callable;
 use function serialize;
 use function sort;
 use const SORT_NATURAL;
@@ -183,4 +186,48 @@ public function unify(
 
         return $instance;
     }
+
+    public function fill(int $startIndex, int $amount, $value): OrderedListInterface
+    {
+        Assert::greaterThanEq($startIndex, 0, 'Given $startIndex must be greater than or equal to %2$s. Got: %s');
+        Assert::greaterThanEq($amount, 1, 'Given $amount must be greater than or equal to %2$s. Got: %s');
+        Assert::lessThanEq(
+            $startIndex,
+            $this->count(),
+            'Give $startIndex must be less than or equal to %2$s to keep the list a continious list. Got: %s.'
+        );
+
+        $instance = clone $this;
+
+        /** @psalm-var list<TValue> $combined */
+        $combined = array_replace(
+            $this->data,
+            $this->createListFilledWithValues($startIndex, $amount, $value)
+        );
+
+        $instance->data = $combined;
+
+        return $instance;
+    }
+
+    /**
+     * @psalm-param TValue|Closure(int $index):TValue $value
+     *
+     * @psalm-return array<int,TValue>
+     */
+    private function createListFilledWithValues(int $start, int $amount, $value): array
+    {
+        if (!is_callable($value)) {
+            /** @psalm-var array<int,TValue> $list */
+            $list = array_fill($start, $amount, $value);
+            return $list;
+        }
+
+        $list = [];
+        for ($index = $start; $index <= $amount; $index++) {
+            $list[$index] = $value($index);
+        }
+
+        return $list;
+    }
 }
diff --git a/src/OrderedListInterface.php b/src/OrderedListInterface.php
index 5548ec7..80cb2da 100644
--- a/src/OrderedListInterface.php
+++ b/src/OrderedListInterface.php
@@ -3,6 +3,8 @@
 
 namespace Boesing\TypedArrays;
 
+use InvalidArgumentException;
+
 /**
  * @template         TValue
  * @template-extends ArrayInterface<int,TValue>
@@ -91,4 +93,12 @@ public function unify(
         ?callable $unificationIdentifierGenerator = null,
         ?callable $callback = null
     ): OrderedListInterface;
+
+    /**
+     * @psalm-param TValue|Closure(int $index):TValue $value
+     * @psalm-return OrderedListInterface<TValue>
+     * @psalm-immutable
+     * @throws InvalidArgumentException if start index does is not fitting in the current list state.
+     */
+    public function fill(int $startIndex, int $amount, $value): OrderedListInterface;
 }
diff --git a/tests/GenericOrderedListTest.php b/tests/GenericOrderedListTest.php
index 8a5c141..500a245 100644
--- a/tests/GenericOrderedListTest.php
+++ b/tests/GenericOrderedListTest.php
@@ -12,8 +12,10 @@
 use PHPUnit\Framework\TestCase;
 use stdClass;
 use Webmozart\Assert\Assert;
+use function array_fill;
 use function chr;
 use function md5;
+use function mt_rand;
 use function spl_object_hash;
 use function strnatcmp;
 
@@ -701,4 +703,135 @@ public function testToMapConversionErrorsOnIntegerishKeys(): void
             return (string) $value;
         });
     }
+
+    /**
+     * @template     TValue
+     * @psalm-param list<TValue> $initial
+     * @psalm-param TValue       $fillUp
+     * @dataProvider invalidStartIndices
+     */
+    public function testFillWillThrowExceptionWhenStartIndexIsInvalid(
+        int $startIndex,
+        array $initial,
+        $fillUp,
+        string $expectedExceptionMessage
+    ): void {
+        $list = new GenericOrderedList($initial);
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage($expectedExceptionMessage);
+        $list->fill($startIndex, mt_rand(1, 10), $fillUp);
+    }
+
+    /**
+     * @template     TValue
+     * @psalm-param TValue $value
+     * @dataProvider scalarFillValues
+     */
+    public function testFillAppendsScalarValues(int $amount, $value): void
+    {
+        self::assertIsScalar($value);
+        /** @var OrderedListInterface<TValue> $list */
+        $list = new GenericOrderedList([]);
+        $list = $list->fill(0, $amount, $value);
+        self::assertEquals(array_fill(0, $amount, $value), $list->toNativeArray());
+    }
+
+    /**
+     * @template mixed
+     * @psalm-return Generator<string,array{0:int,1:list<mixed>,2:mixed,3:non-empty-string}>
+     */
+    public function invalidStartIndices(): Generator
+    {
+        yield 'negative' => [
+            -1,
+            [],
+            0,
+            'Given $startIndex must be greater than or equal to',
+        ];
+
+        yield 'non continues index' => [
+            1,
+            [],
+            0,
+            'to keep the list a continious list.',
+        ];
+
+        yield 'non continues index #2' => [
+            10,
+            [0, 1, 2,],
+            3,
+            'to keep the list a continious list.',
+        ];
+    }
+
+    /**
+     * @psalm-return Generator<string,array{0:int,1:mixed}>
+     */
+    public function scalarFillValues(): Generator
+    {
+        yield 'int' => [
+            1,
+            0,
+        ];
+
+        yield 'string' => [
+            99,
+            'foo',
+        ];
+
+        yield 'float' => [
+            10,
+            0.1,
+        ];
+
+        yield 'true' => [
+            8,
+            true,
+        ];
+
+        yield 'false' => [
+            50,
+            false,
+        ];
+    }
+
+    public function testFillUsesCallbackToGenerateValue(): void
+    {
+        $callback = static function (int $index): string {
+            return chr($index + 65);
+        };
+
+        /** @var OrderedListInterface<string> $list */
+        $abc = new GenericOrderedList([]);
+        $abc = $abc->fill(0, 25, $callback);
+
+        self::assertEquals([
+            'A',
+            'B',
+            'C',
+            'D',
+            'E',
+            'F',
+            'G',
+            'H',
+            'I',
+            'J',
+            'K',
+            'L',
+            'M',
+            'N',
+            'O',
+            'P',
+            'Q',
+            'R',
+            'S',
+            'T',
+            'U',
+            'V',
+            'W',
+            'X',
+            'Y',
+            'Z',
+        ], $abc->toNativeArray());
+    }
 }