Overweight and obesity are chronic, complex, and relapsing diseases occurring across the age span and are caused by genetic, biological, economic, environmental, psychosocial, and behavioral determinants. Therefore, clinical identification and assessment of obesity and treatment responses are multifaceted and wide-ranging. Identification and assessment of overweight and obesity in children, adolescents, and adults are critical for appropriate patient discussion and care decision-making, safety and risk mitigation, and overall outcomes. The clinical assessment of overweight and obesity consists of the comprehensive history, physical examination, vital signs, screenings, questionnaires, laboratory and clinical markers, risk stratification, monitoring, and reassessment of therapy-decision making. Appropriate provision of care for overweight and obesity requires ongoing clinical assessment over the course of a patient-provider relationship and patient’s lived experiences.