Operational models of the household activity-scheduling process have emerged recently. These models replicate the sequence of decisions that leads to observed patterns of human activities and travel, including which activities to conduct, with whom, for how long, at what time and location, and by what mode. Activity priority has been suggested as an important dimension in such scheduling models, particularly as a determinant for the choice and sequencing of activities. The importance of intrahousehold interactions, joint activities in particular, has led to a rapid expansion of research on this topic. However, within most scheduling models, joint activities have been addressed, at best, by assuming that they are preplanned relative to independent activities. Within this context, two important issues concerning the planning of joint activities are explored: the extent to which joint activities are preplanned and whether male and female householders share the same priority when scheduling joint activities. The data set used for the study was the 2003 Computerized Household Activity Scheduling Elicitor survey for Toronto, Ontario, Canada, which recorded information about when a particular activity was planned by respondents. In the analysis, bivariate probit models are estimated for two scheduling alternatives (impulsive or preplanned) for husband and wife. Overall, the empirical results highlight the need to move beyond static priority assumptions for determining the sequencing of activities to develop a behaviorally sound model for activity scheduling. Furthermore, differences in planning priority across individual participants should be taken into account.