The authors determined the validity and reliability of their Past Year Total Physical Activity Questionnaire (PYTPAQ), which assesses the frequency, duration, and intensity of occupational, household, and recreational activities performed over the past year. The PYTPAQ was completed twice at baseline, 9 weeks apart (on average), by 154 healthy Canadian men and women aged 35-65 years for assessment of reliability. The PYTPAQ was completed again 1 year later as a self-administered questionnaire. Four times during the year, participants wore an accelerometer for 7 days and completed 7-day physical activity logs. The authors assessed validity by comparing PYTPAQ summary values with 1-year averages of the physical activity logs and accelerometer data and with physical fitness and anthropometric data measured at baseline and 1 year. Spearman correlations for reliability (metabolic equivalent-hours/week) were 0.64 for total activity, 0.70 for occupational activity, 0.73 for recreational activity, and 0.65 for household activity. For total activity, the intraclass correlation coefficient for correlation between the PYTPAQ and the 7-day physical activity logs was 0.42 (95% confidence interval: 0.28, 0.54), and for the accelerometer data it was 0.18 (95% confidence interval: 0.03, 0.32). Spearman correlations between PYTPAQ hours/week of vigorous activity and maximal oxygen uptake were 0.37 and 0.32 at baseline and follow-up, respectively. In general, the PYTPAQ has acceptable reliability and validity for measurement of past-year physical activity that is comparable to that of similar questionnaires.