This chapter discusses the clinical value of assessing older adults’ social isolation, loneliness, and social relationships. Social relationships are fundamentally important to the health of older adults. It incorporate quantitative factors including size of social networks, degrees of social engagement, number of and time engaged in activities, and amount of social support. The chapter is organized as follows. It first defines isolation, loneliness, and their health related effects. It then implements the assessment of late-life social relationships in clinical practice. The chapter discusses the importance of assessment of late-life social relationships in clinical practice. Clinicians are encouraged to routinely provide feedback to patients, their families, and other healthcare providers about the potential implications of unique social relationship factors on health. These practices promote transparency and communication between provider and patient, as well as between treatment team members, resulting in more effective delivery of care to the fast-growing older adult community.