Objective.-This study sought to compare ambulatory physical activity (PA) between young adults with migraine, tensiontype headache (TTH), and non-headache controls and determine if differences in PA were attributable to headache activity or other relevant covariates. Background.-PA has been implicated in the development, manifestation, and treatment of various headache disorders. However, objective quantification of PA across headache types is lacking, and no study has quantified both prospective PA and the influence of headache occurrence on PA. Methods.-A prospective cohort study followed university participants with migraine, with TTH, or without headache for 7 days using an Omron HJ-112 pedometer and daily headache diaries. Daily free-living PA was compared between groups, and differences in PA as a function of headache day vs non-headache day were compared among those with migraine and TTH. Results.-The final sample consisted of 516 observations from 100 young adults (81/100 female, mean age = 19.0 ± 1.7) comprised of 28 individuals with migraine, 37 individuals with TTH, and 35 non-headache controls. On average, individuals with migraine engaged in less total PA than non-headache controls (6847 vs 8573 steps/day; mean difference = −1726 [95% CI: −3135 to −318], P = .017) across the 7-day monitoring period. After adjusting for relevant covariates (psychological symptoms, body mass index, weekend vs weekday), this difference was evident on both non-headache days (adjusted mean = 5987 vs 8610, P = .002) and headache days (adjusted mean = 6986 vs 9958, P = .017). In contrast, PA of individuals with TTH (mean = 7691 steps/day) did not significantly differ from those with migraine. PA within groups as a function of headache day (vs non-headache day) did not significantly differ for individuals with migraine (mean = 7357 vs 6191, P = .061) or individuals with TTH (mean = 7814 vs 7641, P = .736). Conclusions.-Consistent with other studies, individuals with migraine reported lower levels of PA compared to non-headache controls. Notably, relative reductions in PA occurred even on days in which headache was not experienced and were not attributable to the examined covariates, instead supporting a more global pattern of reduced PA. Further research is needed to isolate the mechanisms underlying interictal reductions in PA among those with migraine.