Objective: There is substantial evidence that poorly designed and reported research can mislead decision making in clinical care. This review investigates the methodological quality of Swedish trials of a wide array of psychological and social interventions. Method: The review includes 302 articles published in peer-reviewed journals during 1990-2014, which evaluated a psychological or social intervention; included a randomized or nonrandomized control group with a pre-post- or pre-follow-up design; and targeted individuals in order to prevent or rehabilitate from physical, psychological, or social problems. The results are based on the information reported in the articles. Results: Overall, methodological quality increased with time. However, more recent studies contained methodological deficits. For example, few had used blinded data collectors, reported power analyses, or searched for adverse events. Conclusion: The results indicate a potential risk of biased results in both older and newer trials. Possible implications for practice and research are discussed. [Paper presented at the Stockholm Conference on Behavioral and Social Intervention Research, 11-12 May, 2017.]