Evidence-based assessment of pediatric bipolar disorder has advanced rapidly in the last two decades, moving from isolated clinical case descriptions to what is now a portfolio of techniques that include checklists from multiple informants, semi-structured diagnostic interviews and severity ratings, and technologies that allow daily tracking of mood and energy over the course of treatment. This review critically appraises (a) the need for evidence-based assessment of bipolar disorder as a common component of clinical practice, (b) triggers that warrant assessment of bipolar, (c) when best to deploy different techniques over the course of diagnosis and treatment, and (d) promising new developments in assessment. A decision-making framework is adapted from evidence-based medicine to guide assessment sequences in a patient-centered approach. Emphasis is placed on approaches that currently have the best validity and are feasible in most clinical practice settings. These methods increase accuracy and address many controversies surrounding pediatric bipolar diagnoses.