Several activity-based models made the transition to practice over the last decade. However, modeling dynamic activity generation and especially, the mechanisms underlying activity generation are not well incorporated in the current activity-based models. This paper describes a first step in estimating the parameters of a need-based activity generation model. A survey was carried out to collect activity data for a typical week and a specific day among a relatively large sample of individuals. The diary data includes detailed information about activity history and future planning. Furthermore, person-level needs on relevant dimensions were measured using Likert scales. Estimation of the model involves a range of shopping, social, leisure and...