Travel behavior research of the past few years has shown an increasing interest in dynamic activity scheduling. Research was done to analyze factors influencing the actual activity scheduling process by using detailed activity travel data from an extensive data set collected in Flanders (Belgium). A model examines the attributes that influence activity planning; a second model analyzes the factors that affect activity rescheduling. The explanatory variables considered in both models are individual, household, activity, and schedule attributes, and their impact is analyzed by using mixed logit models. Random effects are added to the models to test for within-individual variance. The results reveal that activity and schedule characteristics considerably affect activity planning. The rescheduling model also has several highly significant activity and schedule attributes. Most individual and household attributes considered do not influence activity planning and rescheduling behavior, although strong statistical evidence indicates that individual-specific preferences for planning and rescheduling determine the process of activity scheduling.