Deterministic Parallel Java (DPJ) is an extension of the Java programming language which adds parallel constructs that provide a deterministic programming model for object-oriented languages. The language extensions define a type system that a programmer (or interactive porting tool) can use to annotate Java code with type information, and a compiler can use to type-check that a DPJ program has deterministic semantics, i.e., produces the same visible output for a given input, in all executions. Parallel algorithms that cannot be expressed entirely in the statically checked type system require run-time mechanisms to enforce determinism: two key research goals are to make the type system more expressive and to minimize the need to fall back to run-time techniques. With minor modifications, language extensions should be applicable to other base OO languages, such as and . This work is funded by NSF grants CSA 07-02724 and CNS 07-20772, and by Intel and Microsoft through the UPCRC Illinois.