Java and its library provide powerful concurrency control mechanisms. However, their use can lead to similar synchronization code scattered across multiple classes, synchronization and functional code being tangled together, and similar code being duplicated in many applications. Aspect-oriented (AO) programming makes it possible to address these problems. However, the specific behavior of systems built using AO techniques can be challenging to comprehend. We propose a specification approach to precisely express such systems' critical concurrency and synchronization properties. We illustrate the method with a simple example.