diff --git a/include/plasp/pddl/Expression.h b/include/plasp/pddl/Expression.h
index 862f63d..5542ccb 100644
--- a/include/plasp/pddl/Expression.h
+++ b/include/plasp/pddl/Expression.h
@@ -93,6 +93,8 @@ class Expression
 			Constant,
 			Dummy,
 			Either,
+			Exists,
+			ForAll,
 			Imply,
 			Not,
 			Or,
diff --git a/include/plasp/pddl/expressions/Exists.h b/include/plasp/pddl/expressions/Exists.h
new file mode 100644
index 0000000..d795176
--- /dev/null
+++ b/include/plasp/pddl/expressions/Exists.h
@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__EXISTS_H
+#define __PLASP__PDDL__EXPRESSIONS__EXISTS_H
+
+#include <plasp/pddl/expressions/Quantified.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Exists
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Exists: public Quantified<Exists>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Exists;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif
diff --git a/include/plasp/pddl/expressions/ForAll.h b/include/plasp/pddl/expressions/ForAll.h
new file mode 100644
index 0000000..ee9ea00
--- /dev/null
+++ b/include/plasp/pddl/expressions/ForAll.h
@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__FOR_ALL_H
+#define __PLASP__PDDL__EXPRESSIONS__FOR_ALL_H
+
+#include <plasp/pddl/expressions/Quantified.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ForAll
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class ForAll: public Quantified<ForAll>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::ForAll;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif
diff --git a/include/plasp/pddl/expressions/Quantified.h b/include/plasp/pddl/expressions/Quantified.h
new file mode 100644
index 0000000..ff956ae
--- /dev/null
+++ b/include/plasp/pddl/expressions/Quantified.h
@@ -0,0 +1,140 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__QUANTIFIED_H
+#define __PLASP__PDDL__EXPRESSIONS__QUANTIFIED_H
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Quantified
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+class Quantified: public ExpressionCRTP<Derived>
+{
+	public:
+		template<typename ExpressionParser>
+		static boost::intrusive_ptr<Derived> parse(Context &context,
+			ExpressionContext &expressionContext, ExpressionParser parseExpression);
+
+	public:
+		void setArgument(ExpressionPointer argument);
+		ExpressionPointer argument() const;
+
+		ExpressionPointer reduced() override;
+		ExpressionPointer negationNormalized() override;
+
+		void print(std::ostream &ostream) const override;
+
+	protected:
+		Variables m_variables;
+		ExpressionPointer m_argument;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+template<typename ExpressionParser>
+boost::intrusive_ptr<Derived> Quantified<Derived>::parse(Context &context,
+	ExpressionContext &expressionContext, ExpressionParser parseExpression)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("(")
+		|| !parser.testIdentifierAndSkip(Derived::Identifier))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto expression = boost::intrusive_ptr<Derived>(new Derived);
+
+	// Parse variable list
+	parser.expect<std::string>("(");
+	Variable::parseTypedDeclarations(context, expressionContext, expression->m_variables);
+	parser.expect<std::string>(")");
+
+	// Parse argument of the expression
+	expression->Quantified<Derived>::setArgument(parseExpression(context, expressionContext));
+
+	parser.expect<std::string>(")");
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+void Quantified<Derived>::setArgument(ExpressionPointer expression)
+{
+	m_argument = expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+ExpressionPointer Quantified<Derived>::argument() const
+{
+	return m_argument;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+inline ExpressionPointer Quantified<Derived>::reduced()
+{
+	m_argument = m_argument->reduced();
+
+	return this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+inline ExpressionPointer Quantified<Derived>::negationNormalized()
+{
+	m_argument = m_argument->negationNormalized();
+
+	return this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+inline void Quantified<Derived>::print(std::ostream &ostream) const
+{
+	ostream << "(" << Derived::Identifier << "(";
+
+	for (size_t i = 0; i < m_variables.size(); i++)
+	{
+		if (i > 0)
+			ostream << " ";
+
+		ostream << m_variables[i]->name();
+	}
+
+	ostream << ") ";
+
+	m_argument->print(ostream);
+
+	ostream << ")";
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif
diff --git a/src/plasp/pddl/Expression.cpp b/src/plasp/pddl/Expression.cpp
index 4cc2030..9a07b55 100644
--- a/src/plasp/pddl/Expression.cpp
+++ b/src/plasp/pddl/Expression.cpp
@@ -5,6 +5,8 @@
 #include <plasp/pddl/ExpressionContext.h>
 #include <plasp/pddl/IO.h>
 #include <plasp/pddl/expressions/And.h>
+#include <plasp/pddl/expressions/Exists.h>
+#include <plasp/pddl/expressions/ForAll.h>
 #include <plasp/pddl/expressions/Imply.h>
 #include <plasp/pddl/expressions/Not.h>
 #include <plasp/pddl/expressions/Or.h>
@@ -86,14 +88,16 @@ ExpressionPointer parsePreconditionExpression(Context &context,
 	if ((expression = expressions::And::parse(context, expressionContext, parsePreconditionExpression)))
 		return expression;
 
+	if ((expression = expressions::ForAll::parse(context, expressionContext, parsePreconditionExpression)))
+		return expression;
+
 	const auto position = parser.position();
 
 	parser.expect<std::string>("(");
 
 	const auto expressionIdentifierPosition = parser.position();
 
-	if (parser.testIdentifierAndSkip("forall")
-		|| parser.testIdentifierAndSkip("preference"))
+	if (parser.testIdentifierAndSkip("preference"))
 	{
 		// TODO: refactor
 		parser.seek(expressionIdentifierPosition);
@@ -119,6 +123,8 @@ ExpressionPointer parseExpression(Context &context, ExpressionContext &expressio
 
 	if ((expression = expressions::And::parse(context, expressionContext, parseExpression))
 	    || (expression = expressions::Or::parse(context, expressionContext, parseExpression))
+	    || (expression = expressions::Exists::parse(context, expressionContext, parseExpression))
+	    || (expression = expressions::ForAll::parse(context, expressionContext, parseExpression))
 		|| (expression = expressions::Not::parse(context, expressionContext, parseExpression))
 	    || (expression = expressions::Imply::parse(context, expressionContext, parseExpression))
 	    || (expression = expressions::Predicate::parse(context, expressionContext)))
@@ -132,9 +138,7 @@ ExpressionPointer parseExpression(Context &context, ExpressionContext &expressio
 
 	const auto expressionIdentifierPosition = parser.position();
 
-	if (parser.testIdentifierAndSkip("exists")
-		|| parser.testIdentifierAndSkip("forall")
-		|| parser.testIdentifierAndSkip("-")
+	if (parser.testIdentifierAndSkip("-")
 		|| parser.testIdentifierAndSkip("=")
 		|| parser.testIdentifierAndSkip("*")
 		|| parser.testIdentifierAndSkip("+")
diff --git a/src/plasp/pddl/expressions/Exists.cpp b/src/plasp/pddl/expressions/Exists.cpp
new file mode 100644
index 0000000..5169f5e
--- /dev/null
+++ b/src/plasp/pddl/expressions/Exists.cpp
@@ -0,0 +1,25 @@
+#include <plasp/pddl/expressions/Exists.h>
+
+#include <algorithm>
+#include <iostream>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Exists
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string Exists::Identifier = "exists";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
diff --git a/src/plasp/pddl/expressions/ForAll.cpp b/src/plasp/pddl/expressions/ForAll.cpp
new file mode 100644
index 0000000..566d516
--- /dev/null
+++ b/src/plasp/pddl/expressions/ForAll.cpp
@@ -0,0 +1,25 @@
+#include <plasp/pddl/expressions/ForAll.h>
+
+#include <algorithm>
+#include <iostream>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ForAll
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string ForAll::Identifier = "forall";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}