Purpose: To determine which impairments, activity limitations and personal factors at hospital discharge poststroke predict volume, frequency, and intensity of walking activity 1, 3, and 6 months later. Materials and Methods: Prospective longitudinal observational study. Thirty-six people with stroke (71 SD 14 years, 69% male) were recruited at hospital discharge and predictors including fatigue, mood, executive function, walking speed, walking endurance, age, prestroke activity, self-efficacy, and perceived stroke recovery and health were collected. At 1, 3, and 6 months follow-up, participants wore an ActivPAL™ accelerometer to collect measures of walking activity. Results: At 1 month, walking endurance predicted all walking activity (R 2 > 0.29, p < 0.01). At 3 months, walking endurance and prestroke activity predicted activity volume and intensity (R 2 = 0.46–0.61, p < 0.001), and prestroke activity predicted activity frequency (R 2 = 0.31, p = 0.004). At 6 months, age-predicted activity volume and frequency (R 2 = 0.34–0.35, p < 0.003), while prestroke activity, discharge walking endurance, and executive function together predicted activity intensity (R 2 = 0.79, p < 0.001). Conclusion: Walking endurance contributes to walking activity outcomes across the first 6 months following hospital discharge poststroke. After 1 month of discharge, factors other than poststroke changes also contribute to activity outcomes, and should be considered when targeting poststroke physical activity.Implications for rehabilitation Walking endurance should be addressed during stroke rehabilitation as higher scores are linked to more walking activity in the first month after discharge. Prestroke factors such as low prestroke activity levels and older age predict reduced walking activity after stroke, so approaches to address barriers these factors may pose are needed in people with stroke. Physical activity interventions should be tailored to the individual, their environment, and context, and take into consideration prestroke factors.