Methods and compositions for identifying an agent (e.g., a gene product or small molecule compound) that modulates a Parkinson's disease phenotype are provided. In practicing the subject methods, a non-mammalian animal model, such as Drosophila melanogaster, that includes a mutant parkin gene and at least one other mutant gene are evaluated for a Parkinson's disease phenotype. Also provided are kits, and systems for practicing the subject methods, as well as methods of use of agents identified in the screening method of the invention.