In 2006, PAIN published a systematic review of the measurement properties of self-report pain intensity measures in children and adolescents (Stinson JN, Kavanagh T, Yamada J, Gill N, Stevens B. Systematic review of the psychometric properties, interpretability and feasibility of self-report pain intensity measures for use in clinical trials in children and adolescents. PAIN 2006;125:143–57). Key developments in pediatric pain necessitate an update of this work, most notably growing use of the 11-point numeric rating scale (NRS-11). Our aim was to review the measurement properties of single-item self-report pain intensity measures in children 3 to 18 years old. A secondary aim was to develop evidence-based recommendations for measurement of child and adolescent self-report of acute, postoperative, and chronic pain. Methodological quality and sufficiency of measurement properties for reliability, validity, responsiveness, and interpretability was assessed by at least 2 investigators using COnsensus based Standards for the selection of health Measurement INstruments (COSMIN). Searches identified 60 unique self-report measures, of which 8 (reported in 80 papers) met inclusion criteria. Well-established measures included the NRS-11, Color Analogue Scale (CAS), Faces Pain Scale–Revised (FPS-R; and original FPS), Pieces of Hurt, Oucher—Photographic and Numeric scales, Visual Analogue Scale, and Wong-Baker FACES Pain Rating Scale (FACES). Quality of studies ranged from poor to excellent and generally reported sufficient criterion and construct validity, and responsiveness, with variable reliability. Content and cross-cultural validity were minimally assessed. Based on available evidence, the NRS-11, FPS-R, and CAS were strongly recommended for self-report of acute pain. Only weak recommendations could be made for self-report measures for postoperative and chronic pain. No measures were recommended for children younger than 6 years, identifying a need for further measurement refinement in this age range. Clinical practice and future research implications are discussed.