Bipolar and related disorders are complex conditions resulting in a significant level of impairment. Due to the complexity of the disorder, diagnosis of bipolar disorder can be difficult. Genetic history, sociodemographic factors, stress, and trauma history can contribute to the development of bipolar disorder and must be considered during a diagnostic assessment. The use of semi-structured interviews, structured assessments, or screening measures may aid in the diagnosis of bipolar disorder and should be used at an assessor’s discretion. Combining multiple assessment tools (e.g., conducting a semi-structured interview and utilizing a structured assessment) may result in the most complete diagnosis. Including information received from the individual’s family or close friends in the assessment process can be especially beneficial and may increase the likelihood of a proper diagnosis early on. Many social and cultural constructs can have an impact on bipolar disorder diagnosis and must be considered by the assessor, especially for historically underrepresented populations. In addition, because individuals diagnosed with bipolar disorder are at a higher risk of suicide attempt than the general population, a safety assessment should always be conducted. Despite the complexity of diagnosing bipolar and related disorders, proper diagnosis is critical to ensuring individuals receive a proper treatment plan with the goal of decreasing debilitating symptoms.