Changes in neighborhood crime may effect participation in active lifestyles and, consequently, the success of interventions aimed at increasing physical activity or reducing sedentary time. Previous research, however, has tended to rely on cross-sectional data and perceptions of crime, rather than longitudinal studies of reported crime rates. PURPOSE: We examined whether changes in sedentary time were associated with a change in neighborhood crime in people aged 45 years and older. METHODS: Fixed effects linear regression were used to assess the degree of association between self-reported sitting time and five tertile-based measures of neighborhood crime: non-domestic violence; malicious damage; break and enter; stealing, theft and robbery; and an aggregated ‘total crime’ measure. Sitting time data was sourced from the baseline dataset of The 45 and Up Study (a large-scale cohort study of health and social phenomena across New South Wales, Australia) and from the Social, Economic and Environmental Factors (SEEF) Study (a sub-study of The 45 and Up Study). Crime data were provided by the NSW Bureau of Crime Statistics and Research. Gender-stratified analyses were fitted for 24,053 men and 27,169 women who remained in the same Statistical Local Area (a unit of geography comprising on average of 32,000 residents) between baseline (45 and Up assessment) and follow-up (SEEF assessment), and were adjusted for time-variant confounders (age, income, economic status, couple status, and physical health). RESULTS: Fully adjusted models indicated an increase in sitting time is associated with an increase in neighborhood crime for men and women. An increase in non-domestic violence from tertile 1 (low) to tertile 3 (high) coincided with an increase in sitting time among men, (β=0.41, 95%CI 0.23, 0.59), and women (β=0.23, 95%CI 0.08, 0.39). Larger effect sizes were observed for a tertile 1-to-3 increase in malicious damage for men (β=0.62, 95%CI 0.49, 0.76) and women (β=0.49, 95%CI 0.38, 0.61). CONCLUSIONS: Increasing levels of neighborhood crime, especially types which influence the local built environment, may increase sedentary behaviour and discourage active lifestyles. Investments in crime prevention are investments in health promotion.