Orthopedic sports medicine studies, like any field of clinical research, are susceptible to various forms of bias and possible confounding. Given the importance that drawing correct and valid conclusions has in medicine, it is imperative that researchers and clinicians are acutely aware of potential sources of bias when designing and conducting a study or when reviewing the literature to inform patient care. Determining the best strategies to prevent, minimize, or control for potential sources of bias and confounding must be a part of the research process from initial design to publication. When reviewing studies, clinicians must consider all possible extrinsic factors that may have introduced bias in a trial and how the presence of such factors may impact the conclusions and clinical utility of the findings. This chapter outlines many of the sources of bias and confounding most relevant to orthopedic sports medicine during various stages of the research process.