Purpose: To describe the development and preliminary evaluation of the Multicontext Sitting Time Questionnaire (MSTQ). Method: During development of the MSTQ, contexts and domains of sitting behavior were utilized as recall cues to improve the accuracy of sitting assessment. The terms "workday" and "nonworkday" were used to disambiguate occupational and discretionary sitting. An expert panel evaluated content validity. Among 25 participants, test-retest reliability of the MSTQ items was assessed with intraclass correlation coefficients (ICCs). Convergent validity was assessed versus relative and absolute accelerometer-estimated sedentary time and activity log using Pearson ("r") or Spearman ("?") correlation coefficients where appropriate. Results: Pilot testing revealed Web-based MSTQ administration was rapid, scalable, and inexpensive. Most items in the MSTQ demonstrated acceptable reliability (ICCs > 0.70). Compared with accelerometer-estimated sedentary time relative to total wear time, the MSTQ exhibited a low correlation on workdays ("r" = 0.34) and a moderately high correlation on nonworkdays ("r" = 0.61). Conclusions: The systematic development of the MSTQ resulted in several improvements over previous tools and may serve as a model for purpose-driven questionnaire design. Additional validation is needed to conclusively determine the utility of the MSTQ.