To evaluate the effects of Mind Over Matter: Healthy Bowels, Healthy Bladder, a small-group intervention, on urinary and bowel incontinence symptoms among older women with incontinence. In this individually randomized group treatment trial, women aged 50 years and older with urinary, bowel incontinence, or both, were randomly allocated at baseline to participate in Mind Over Matter: Healthy Bowels, Healthy Bladder immediately (treatment group) or after final data collection (waitlist control group). The primary outcome was urinary incontinence (UI) improvement on the Patient Global Impression of Improvement at 4 months. Validated instruments assessed incontinence, self-efficacy, depression, and barriers to care-seeking. Intent-to-treat analyses compared differences between groups. Target sample size, based on an anticipated improvement rate of 45% in treated women vs 11% in the control group, 90% power, type I error of 0.05, with anticipated attrition of 25%, was 110. Among 121 women randomized (62 treatment group; 59 control group), 116 (95%) completed the 4-month assessment. Most participants were non-Hispanic white (97%), with a mean age of 75 years (SD 9.2, range 51-98); 66% had attended some college. There were no significant between-group differences at baseline. At 4 months, 71% of treated women vs 23% of women in the control group reported improved UI on Patient Global Impression of Improvement (P<.001); 39% vs 5% were much improved (P<.001). Regarding bowel incontinence, 55% of treated women vs 27% of women in the control group improved on Patient Global Impression of Improvement (P<.005), with 35% vs 11% reporting much improvement (P<.005). Treated women improved significantly more than women in the control group on all validated instruments of incontinence severity, quality of life, and self-efficacy. Care-seeking rates were similar between groups. Participation in a small-group intervention improves symptoms of both urinary and bowel incontinence in older women. Mind Over Matter is a feasible model with potential to bring effective behavioral solutions to the community. ClinicalTrials.gov, NCT03140852.