The development of thin polymer films that provide precise control over drug release profiles could lead to significant advances in the fields of drug and gene delivery, tissue engineering, and adjacent areas of biotechnology. We have adapted a process for the layer-by-layer (LBL) deposition of charged polymers on surfaces to the fabrication of thin (e.g., 10-600 Å) biodegradable films. The LBL process is a versatile and inexpensive method for the construction of thin films, often with nanometer-scale control over the spatial distribution of ionized species within the film. Through the synthesis and deposition of new degradable cationic polymers, we have constructed films that erode under physiological conditions and that are suitable for the release of functional polyanions such as DNA. The ability to control release rates through judicious design of polymer structure could allow the tuning of these systems for a broad range of delivery applications.