Methods and compositions for systemically or locally administering a beneficial agent to a subject are described, and include, for example, implantable elastomeric depot compositions that can be injected into a desired location and which can provide controlled release of a beneficial agent over a prolonged duration of time. The compositions include a biocompatible, elastomeric polymer, a biocompatible solvent having low water miscibility that forms an elastomeric viscous gel with the polymer and limits water uptake by the implant, and a beneficial agent.