I have a class that stores a collection of Java 5 enums. However, when trying to unmarshall the object, I get the following error: ava.lang.IllegalArgumentException: java.util.Collection is not an enum type at java.lang.Class.enumConstantDirectory(Class.java:2895) at java.lang.Enum.valueOf(Enum.java:187) at org.compass.core.converter.basic.EnumConverter.fromString(EnumConverter.java:31) at org.compass.core.converter.basic.AbstractBasicConverter.unmarshall(AbstractBasicConverter.java:84) at org.compass.core.converter.mapping.osem.ClassPropertyMappingConverter.unmarshall(ClassPropertyMappingConverter.java:61) at org.compass.core.converter.mapping.osem.AbstractCollectionMappingConverter.unmarshall(AbstractCollectionMappingConverter.java:139) at org.compass.core.converter.mapping.osem.ClassMappingConverter.unmarshall(ClassMappingConverter.java:236) at org.compass.core.marshall.DefaultMarshallingStrategy.unmarshall(DefaultMarshallingStrategy.java:153) at org.compass.core.marshall.DefaultMarshallingStrategy.unmarshall(DefaultMarshallingStrategy.java:145) at org.compass.core.impl.DefaultCompassSession.getByResource(DefaultCompassSession.java:229) at org.compass.core.impl.DefaultCompassSession.getByResource(DefaultCompassSession.java:218) at org.compass.core.impl.DefaultCompassSession.get(DefaultCompassSession.java:198) My class is defined something like this: public class MyClass { Collection<MyEnum> getSomething() { ... } void setSomething(Collection<MyEnum> values) { ... } } My mapping file (.cpm.xml) has this in the mapping for this class: <property name="something"> <meta-data index="un_tokenized" >something</meta-data> </property> It appears that the EnumConverter is relying on the return type of the class getter method, instead of the enum type defined using generics.