This report contains recommendations to aid those concerned with photochemical modeling in planning studies. The suggested programs are designed to provide information needed to develop kinetic models to describe the chemical transformations of atmospheric pollutants. The core of this report focuses on kinetic and mechanistic studies of individual reactions, smog chamber studies, and atmospheric measurement programs that the authors feel should be undertaken to provide the necessary data for model development. Existing deficiencies in knowledge in each of these areas are discussed and the types of programs needed to provide the missing information are examined in detail. The report also includes a short history of model development, describing the various photochemical mechanisms developed to date. (Author)