© 2017 Human Kinetics, Inc. Background: The current study evaluated the feasibility and effectiveness of a diet and physical activity intervention for homeless adults. Methods: Shelter residents (N = 32) were randomly assigned to a 4-week diet and physical activity intervention (n = 17) or an assessment-only control group (n = 15). Intervention participants received tailored educational newsletters, pedometers with step goals, and twice daily fruit/vegetable snacks. Key measures included 24-hour dietary recall interviews and accelerometer-measured moderate-to-vigorous intensity physical activity (MVPA). Results: At baseline, 68.8% of participants were overweight or obese, 93.8% reported food insecurity, and 43.8% reported activity levels below physical activity guidelines. Baseline dietary recall interviews indicated low fruit/vegetable consumption, and elevated intake of added sugar, saturated fat, and sodium relative to current dietary recommendations. During the 4-week study period, intervention participants engaged in significantly greater accelerometer-measured daily MVPA (P < .001) than controls (median = 60 daily minutes p vs. 41 daily minutes). Between groups differences in fruit/vegetable consumption at the end of treatment did not reach statistical significance. Most participants reported that the intervention was helpful for increasing fruit/vegetable intake and physical activity. Conclusions: Findings highlight the potential to improve dietary quality and increase physical activity among sheltered homeless adults.