This chapter provides guidelines for psychologists to use when assessing behavioral, social, and emotional functioning of culturally and linguistically diverse (CLD) children and adolescents. It begins by describing the typical methods psychologists use to assess these areas, and analyzing them in terms of their effectiveness and validity with CLD children and teens. The chapter then proposes that psychologists use an adaptation of Mash and Hunsley’s developmental systems approach (DSA) to assess CLD children and adolescents. It then discusses specific issues involved in assessment of CLD children and adolescents who display inattentive and hyperactive–impulsive behaviors, externalizing behaviors, internalizing behaviors, and severe social problems. The chapter specifically addresses questions involving the use of the Diagnostic and Statistical Manual of Mental Disorders with CLD children and adolescents to diagnose specific disorders such as attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder, anxiety and mood disorders, and autism spectrum disorders (ASDs).