diff --git a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlock.java b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlock.java
index 789fa8f0f..72e2801ff 100644
--- a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlock.java
+++ b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlock.java
@@ -16,11 +16,24 @@ public interface AbstractBlock extends AbstractNode {
      */
     String style();
     String getStyle();
+
     /**
+     * @return The list of child blocks of this block
      * @deprecated Please use {@linkplain #getBlocks()} instead
      */
     List<AbstractBlock> blocks();
+
+    /**
+     * @return The list of child blocks of this block
+     */
     List<AbstractBlock> getBlocks();
+
+    /**
+     * Appends a new child block as the last block to this block.
+     * @param block The new child block added as last child to this block.
+     */
+    void append(AbstractBlock block);
+
     /**
      * @deprecated Please use {@linkplain #getContent()} instead
      */
diff --git a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlockImpl.java b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlockImpl.java
index 02878af93..1a3a101df 100644
--- a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlockImpl.java
+++ b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractBlockImpl.java
@@ -53,6 +53,12 @@ public List<AbstractBlock> getBlocks() {
         return new RubyBlockListDecorator<AbstractBlock>(rubyBlocks);
     }
 
+    @Override
+    public void append(AbstractBlock block) {
+
+        getRubyObject().callMethod(runtime.getCurrentContext(), "<<", ((AbstractBlockImpl) block).getRubyObject());
+    }
+
     @Override
     public Object content() {
         return getContent();
diff --git a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNode.java b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNode.java
index 9adebe732..f168c8356 100644
--- a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNode.java
+++ b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNode.java
@@ -16,6 +16,8 @@ public interface AbstractNode {
      */
     String getId();
 
+    void setId(String id);
+
     String getNodeName();
     /**
      * @deprecated Use {@linkplain #getParent()}  instead.
diff --git a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNodeImpl.java b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNodeImpl.java
index d9a508f48..aefceaffc 100644
--- a/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNodeImpl.java
+++ b/asciidoctorj-core/src/main/java/org/asciidoctor/ast/AbstractNodeImpl.java
@@ -27,6 +27,11 @@ public String getId() {
         return getString("id");
     }
 
+    @Override
+    public void setId(String id) {
+        setString("id", id);
+    }
+
     @Override
     public String context() {
         return getContext();
diff --git a/asciidoctorj-core/src/test/groovy/org/asciidoctor/extension/WhenAnExtensionAppendsChildBlocks.groovy b/asciidoctorj-core/src/test/groovy/org/asciidoctor/extension/WhenAnExtensionAppendsChildBlocks.groovy
new file mode 100644
index 000000000..853d7eb53
--- /dev/null
+++ b/asciidoctorj-core/src/test/groovy/org/asciidoctor/extension/WhenAnExtensionAppendsChildBlocks.groovy
@@ -0,0 +1,65 @@
+package org.asciidoctor.extension
+
+import org.asciidoctor.Asciidoctor
+import org.asciidoctor.OptionsBuilder
+import org.asciidoctor.ast.Block
+import org.asciidoctor.ast.DocumentRuby
+import org.asciidoctor.ast.Section
+import org.jboss.arquillian.spock.ArquillianSputnik
+import org.jboss.arquillian.test.api.ArquillianResource
+import org.jsoup.Jsoup
+import org.jsoup.nodes.Document
+import org.junit.runner.RunWith
+import spock.lang.Specification
+
+@RunWith(ArquillianSputnik)
+class WhenAnExtensionAppendsChildBlocks extends Specification {
+
+    String document = '''= Test document
+
+== Section 1
+
+some text
+
+== Section 2
+
+more text
+
+'''
+
+    @ArquillianResource
+    private Asciidoctor asciidoctor
+
+    def 'should be able to blocks via Block.append'() {
+
+        given:
+
+        final String additionalText = 'Text added by Treeprocessor'
+        asciidoctor.javaExtensionRegistry().treeprocessor(new Treeprocessor() {
+
+            int lastid = 0
+
+            @Override
+            DocumentRuby process(DocumentRuby document) {
+                document.blocks.findAll { block -> block instanceof Section }.each {
+                    block ->
+                        Block newBlock = createBlock(block, 'paragraph', additionalText, [:])
+                        newBlock.id = "NewBlock_${lastid++}"
+                        block.append(newBlock)
+                }
+                document
+            }
+        })
+
+        when:
+        String result = asciidoctor.convert(this.document, OptionsBuilder.options().headerFooter(false))
+
+        then:
+        Document htmlDocument = Jsoup.parse(result)
+        !htmlDocument.select('#NewBlock_0').empty
+        !htmlDocument.select('#NewBlock_1').empty
+        htmlDocument.select('#NewBlock_2').empty
+
+    }
+
+}