The single most commonly reported physical activity in public health surveys is walking. As evidence accumulates that walking is important for preventing weight gain and reducing the risk of diabetes, there is increased need to capture this behavior in a valid and reliable manner. Although the disadvantages of a self-report methodology are well known, it still represents the most feasible approach for conducting population-level surveillance across developed and developing countries. The International Physical Activity Questionnaire (IPAQ) was created and evaluated as a standardized instrument for this purpose. In addition to walking behaviors, IPAQ also assesses time spent in moderate- and vigorous-intensity activity as well as sitting behaviors. Aggregated IPAQ data have been previously validated compared to accelerometers, and overall reliability was confirmed across 12 countries (Craig et al., 2003). Previous research showed criterion validity Spearman correlations with a median of 0.30 and test-retest reliability Spearman correlations clustered around 0.8 (Craig et al., 2003). The purpose of this study, however, was to reanalyze these data with respect to validity (again compared to an accelerometer) and test-retest reliability specifically for population monitoring of walking. (Contains 2 tables.)