Objective: This randomized controlled trial of the online intervention, man therapy (MT), evaluated efficacy to reduce suicidal ideation (SI) and depression among working-aged men. Method: Five-hundred and fifty-four men enrolled and 421 completed all surveys. Control Condition men explored the Healthy Men Michigan (HMM) website and Intervention Condition men explored HMM and MT. Hypotheses included men who used MT would report decreased SI and depression over time compared to Control Condition men. Results: Latent growth curve modeling revealed improvements in SI (slope = −0.23, p < 0.001, 95% CI: −0.29, −0.16) and depression (slope = −0.21, p < 0.001, 95% CI: −0.23, −0.18) over time for men in both groups; however, there was no difference in slope based on group assignment. Depression, lifetimeThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.