Assessing a learner in the course of a hectic emergency department (ED) rotation is a daunting task for both experienced and new supervisors. This is particularly true if the learner is not doing well. In light of numerous impediments provided by the modern ED environment, sticking to basic principles can result in marked improvement in both the process and the outcome of in-training assessment. This article addresses these important principles for assessment as they apply in the clinical realm of the ED, with a focus on matching expectations to both the trainee and the available assessment strategies. It is critical that teachers strive for clarity, consistency, honesty, and adherence to due process in their learner assessments. This article provides an evidence-informed approach to succeeding with such an approach to clinical assessment.