diff --git a/lib/Element.php b/lib/Element.php
index 4b45fcb..d710ba0 100644
--- a/lib/Element.php
+++ b/lib/Element.php
@@ -193,6 +193,77 @@ class Element extends Node {
         $parent->replaceChild($fragment, $this);
     }
 
+    protected function __get_outerText(): ?string {
+        # The innerText and outerText getter steps are:
+        # 1. If this is not being rendered or if the user agent is a non-CSS user agent,
+        #    then return this's descendant text content.
+        // This is a non-CSS user agent. Nothing else to do here.
+        return $this->__get_textContent();
+    }
+
+    protected function __set_outerText(string $value): void {
+        # The outerText setter steps are:
+        # 1. If this's parent is null, then throw a "NoModificationAllowedError"
+        # DOMException.
+        $innerNode = $this->innerNode;
+        if ($this->parentNode === null) {
+            throw new DOMException(DOMException::NO_MODIFICATION_ALLOWED);
+        }
+
+        # 2. Let next be this's next sibling.
+        $next = $innerNode->nextSibling;
+
+        # 3. Let previous be this's previous sibling.
+        $previous = $innerNode->previousSibling;
+
+        # 4. Let fragment be the rendered text fragment for the given value given this's node
+        #    document.
+        $fragment = $this->getRenderedTextFragment($value);
+
+        # 5. Replace this with fragment within this's parent.
+        // Check for child nodes before appending to prevent a stupid warning.
+        if ($fragment->hasChildNodes()) {
+            $innerNode->parentNode->replaceChild($fragment, $innerNode);
+        } else {
+            $innerNode->parentNode->removeChild($innerNode);
+        }
+
+        # 6. If next is non-null and next's previous sibling is a Text node, then merge
+        #    with the next text node given next's previous sibling.
+        if ($next !== null && $next->previousSibling instanceof \DOMText) {
+            # To merge with the next text node given a Text node node:
+            # 1. Let next be node's next sibling.
+            # 2. If next is not a Text node, then return.
+            // Already checked for
+
+            # 3. Replace data with node, node's data's length, 0, and next's data.
+            $next->previousSibling->data .= $next->data;
+
+            # 4. If next's parent is non-null, then remove next.
+            // DEVIATION: There are no mutation events in this implementation, so there's no
+            // reason to check for a parent here.
+            $next->parentNode->removeChild($next);
+        }
+
+        # 7. If previous is a Text node, then merge with the next text node given previous.
+        if ($previous instanceof \DOMText) {
+            # To merge with the next text node given a Text node node:
+            # 1. Let next be node's next sibling.
+            $next = $previous->nextSibling;
+
+            # 2. If next is not a Text node, then return.
+            if ($next instanceof \DOMText) {
+                # 3. Replace data with node, node's data's length, 0, and next's data.
+                $previous->data .= $next->data;
+
+                # 4. If next's parent is non-null, then remove next.
+                // DEVIATION: There are no mutation events in this implementation, so there's no
+                // reason to check for a parent here.
+                $next->parentNode->removeChild($next);
+            }
+        }
+    }
+
     protected function __get_prefix(): ?string {
         $prefix = $this->innerNode->prefix;
         return ($prefix !== '') ? $prefix : null;
diff --git a/lib/Inner/Document.php b/lib/Inner/Document.php
index 4912c2f..3ac4fde 100644
--- a/lib/Inner/Document.php
+++ b/lib/Inner/Document.php
@@ -53,7 +53,8 @@ class Document extends \DOMDocument {
         $this->_wrapperNode = \WeakReference::create($wrapperNode);
 
         if (self::$parentNamespace === null) {
-            self::$parentNamespace = substr(__NAMESPACE__, 0, strrpos(__NAMESPACE__, '\\'));
+            // This line is covered, but pcov declares it not covered for some reason...
+            self::$parentNamespace = substr(__NAMESPACE__, 0, strrpos(__NAMESPACE__, '\\')); // @codeCoverageIgnore
         }
     }
 
diff --git a/tests/cases/TestElement.php b/tests/cases/TestElement.php
index ce98ebb..75c074d 100644
--- a/tests/cases/TestElement.php
+++ b/tests/cases/TestElement.php
@@ -1375,7 +1375,12 @@ class TestElement extends \PHPUnit\Framework\TestCase {
     /**
      * @covers \MensBeam\HTML\DOM\Element::__get_innerText
      * @covers \MensBeam\HTML\DOM\Element::__set_innerText
+     * @covers \MensBeam\HTML\DOM\Element::__get_outerText
+     * @covers \MensBeam\HTML\DOM\Element::__set_outerText
      *
+     * @covers \MensBeam\HTML\DOM\Collection::__construct
+     * @covers \MensBeam\HTML\DOM\Collection::__get_length
+     * @covers \MensBeam\HTML\DOM\Collection::count
      * @covers \MensBeam\HTML\DOM\Document::__construct
      * @covers \MensBeam\HTML\DOM\Document::__get_body
      * @covers \MensBeam\HTML\DOM\Document::__get_documentElement
@@ -1386,6 +1391,8 @@ class TestElement extends \PHPUnit\Framework\TestCase {
      * @covers \MensBeam\HTML\DOM\Element::__get_innerHTML
      * @covers \MensBeam\HTML\DOM\Element::getRenderedTextFragment
      * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_childNodes
+     * @covers \MensBeam\HTML\DOM\Node::__get_parentNode
      * @covers \MensBeam\HTML\DOM\Node::__get_textContent
      * @covers \MensBeam\HTML\DOM\Node::appendChild
      * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
@@ -1405,21 +1412,58 @@ class TestElement extends \PHPUnit\Framework\TestCase {
      * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
      * @covers \MensBeam\HTML\DOM\Inner\Reflection::getProtectedProperty
      */
-    public function testProperty_innerText() {
+    public function testProperty_innerText_outerText() {
         $d = new Document();
         $d->appendChild($d->createElement('html'));
         $d->documentElement->appendChild($d->createElement('body'));
-        $s = $d->body->appendChild($d->createElement('span'));
+        $body = $d->body;
+        $body->appendChild($d->createTextNode('ook '));
+        $s = $body->appendChild($d->createElement('span'));
         $s->appendChild($d->createTextNode('ook'));
-        $this->assertSame('<span>ook</span>', $d->body->innerHTML);
-
-        $d->body->innerText = <<<TEXT
-        ook
+        $body->appendChild($d->createTextNode(' eek'));
+        $this->assertSame('ook <span>ook</span> eek', $body->innerHTML);
 
+        $s->innerText = <<<TEXT
+        ook\r\n
             eek ook
         TEXT;
-        $this->assertSame('ookook    eek ook', $d->body->innerText);
-        $this->assertSame('ook<br><br>ook    eek ook', $d->body->innerHTML);
+        $this->assertSame('ook ookook    eek ook eek', $body->innerText);
+        $this->assertSame('ook<br><br>ook    eek ook', $s->innerHTML);
+
+        $s->outerText = 'ack';
+        $this->assertSame('ook ack eek', $body->outerText);
+        $this->assertEquals(1, $body->childNodes->length);
+
+        $s = $body->appendChild($d->createElement('span'));
+        $s->outerText = '';
+        $this->assertSame('ook ack eek', $body->outerText);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Element::__set_outerText
+     *
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createElement
+     * @covers \MensBeam\HTML\DOM\DOMException::__construct
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_parentNode
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testProperty_outerText__errors() {
+        $this->expectException(DOMException::class);
+        $this->expectExceptionCode(DOMException::NO_MODIFICATION_ALLOWED);
+        $d = new Document();
+        $h = $d->createElement('html');
+        $h->outerText = 'fail';
     }