The use of outcome measures (OMs) in clinical practice has become increasingly important, due to the expectations to account for patient outcomes and justify healthcare expenditures. With the ability to assess patients’ current status and change over time, OMs can inform clinical decision-making and help clinicians and patients better understand their current function and projected recovery. When assessing outcomes, there are five key considerations for clinicians: confidence in a measured value; the extent to which valid inferences can be drawn from a measured value; the extent to which valid inferences concerning a patient’s change status can be made; the patient specific target value; and the ideal reassessment interval. The purpose of this paper is to provide a guide to help clinicians to choose and effectively utilize OMs. We will address the five important application questions to consider, illustrated with clinical examples using the 6-min walk test in different patient populations.