The paper focuses attention on the influence life cycle stages exerts on travel behavior. It presents the family Life cycle concept and its usefulness in the trip generation phase of the urban transportation planning process. The concept refers to the household structure reflected in life cycle stages expressed as the major break points through which a household passes as it evolves. A life cycle classification scheme is formulated using available data from the city of Shiraz in Iran to better explain travel behavior. Different stages in the household life cycle (or family structure) consistent with significant changes of activity time allocation and travel behavior are identified. Disaggregate behavioral trip generation models which incorporate a wide spectrum of independent variables such as household socioeconomic characteristics, family structure and life cycle stage, and land use attributes of residence location were pursued. Based on the assumption of the stage in the life cycle, it is found that there is a significant effect on the estimated number of trips made for different purposes. Stepwise regression analysis is used to test the adequacy of the life cycle based model. Results demonstrate the usefulness of the family life cycle variables in replicating travel behavior through the disaggregate trip generation models.