Assessing learners is foundational to their training and developmental growth throughout the medical education continuum. However, growing evidence shows the prevalence and impact of harmful bias in assessments in medical education, accelerating the urgency to identify solutions. Assessment bias presents a critical problem for all stages of learning and the broader educational system. Bias poses significant challenges to learners, disrupts the learning environment, and threatens the pathway and transition of learners into health professionals. While the topic of assessment bias has been examined within the context of measurement literature, limited guidance and solutions exist for learners in medical education, particularly in the clinical environment. This article presents an overview of assessment bias, focusing on clinical learners. A definition of bias and its manifestations in assessments are presented. Consequences of assessment bias are discussed within the contexts of validity and fairness and their impact on learners, patients/caregivers, and the broader field of medicine. Messick’s unified validity framework is used to contextualize assessment bias; in addition, perspectives from sociocultural contexts are incorporated into the discussion to elaborate the nuanced implications in the clinical training environment. Discussions of these topics are conceptualized within the literature and the interventions used to date. The article concludes with practical recommendations to overcome bias and to develop an ideal assessment system. Recommendations address articulating values to guide assessment, designing assessment to foster learning and outcomes, attending to assessment procedures, promoting continuous quality improvement of assessment, and fostering equitable learning and assessment environments.