Object-oriented programs involve many unique features that are not present in their conventional counterparts. Examples are message passing, synchronization, dynamic binding, object instantiation, persistence, encapsulation, inheritance, and polymorphism. Integration testing for such programs is, therefore, more difficult than that for conventional programs. We present an overview of current work on integration testing for object-oriented and/or concurrent programs, with a view to identifying areas for future research. We cover state-based testing, event based testing, fault-based testing, deterministic and reach ability techniques, and formal and semiformal techniques.