A common hypothesis is that crime is a major barrier to physical activity, but research does not consistently support this assumption. This article advances research on crime-related safety and physical activity by developing a multilevel conceptual framework and reliable measures applicable across age groups.Criminologists and physical activity researchers collaborated to develop a conceptual framework. Survey development involved qualitative data collection and resulted in 155 items and 26 scales. Intraclass correlation coefficients (ICCs) were computed to assess test-retest reliability in a subsample of participants (N = 176). Analyses were conducted separately by age groups.Test-retest reliability for most scales (63 of 104 ICCs across 4 age groups) was "excellent" or "good" (ICC ≥ .60) and only 18 ICCs were "poor" (ICC < .40). Reliability varied by age group. Adolescents (aged 12-17 y) had ICCs above the .40 threshold for 21 of 26 scales (81%). Young adults (aged 18-39 y) and middle-aged adults (aged 40-65 y) had ICCs above .40 for 24 (92%) and 23 (88%) scales, respectively. Older adults (aged 66 y and older) had ICCs above .40 for 18 of 26 scales (69%).The conceptual framework and reliable measures can be used to clarify the inconclusive relationships between crime-related safety and physical activity.