Main Abstract Content: State of the art: With the emergence of web-based interventions in the field ofOrganizational Behavior, we have to pay attention to methodological challenges and pitfalls ofdesigning, conducting, and evaluating intervention studies. Issues of appropriate design andadequate evaluation should be considered essential for both effectiveness of the intervention androbustness of the findings.Contributions: Based on our pre-registered study with a randomized controlled design (N=62), wedemonstrate challenges concerning the design of an intervention aiming to reduce perseverativethinking as the primary outcome in employees. Also, we report issues related to the recruitment andcompliance of participants. We show how researcher degrees of freedom, exploratory as opposed toconfirmatory analyses, (unintentional) p-hacking, and reporting bias might threaten the robustnessand replicability of our findings and bloat effect sizes.Research/Practical Implications: Given that web-based interventions are promising and cost-effective approaches to fostering occupational health, we need to ensure that the implementedprograms do not fail to come up to expectations raised by the research.Value: In this presentation, based on real study and data we demonstrate the most vulnerable pointsin the design and evaluation of intervention studies and suggest alternative strategies that might helpto enhance the quality of intervention research.