Purpose The objective of this thesis is to establish an evidence-based clinical practice guideline for the primary management of obstetrical brachial plexus injury (OBPI). Four gaps are identified for management of OBPI in Canada: 1) The historic poor use of evidence, 2) Timing of referral to multidisciplinary care, 3) Indications and timing of operative nerve repair, and 4) Distribution of expertise in Canada. Methods The guideline is intended for all providers delivering perinatal care, and all specialists delivering care to OBPI patients. The consensus group was composed of clinicians representing each of Canada’s ten multidisciplinary centres. An original systematic review comparing the effectiveness of primary operative versus nonoperative management, and a review of Canadian OBPI epidemiology were completed. Quality indicators for referral to a multidisciplinary centre were established. Recommendations were based on best evidence, and interpretation of this evidence by clinical experts. An electronic modified Delphi approach was used for consensus, with agreement criteria defined a priori following RAND procedures. Results Nerve repair reduces functional impairment in OBPI versus nonoperative management of similar patients, and modern microsurgery has low incidence of major adverse events. The quality of evidence was low. Residual impairment is underestimated and uncharacterized in nonoperative literature. OBPI incidence was at least 1.24 per 1000 births in Canada, and consistent over the study period. The strongest risk factors for OBPI were comorbid humerus fracture, shoulder dystocia and comorbid clavicle fracture. Most patients were not referred to a multidisciplinary centre. The guideline group approved seven recommendations. Discussion Recommendations address the identified gaps in care, and guide identification, referral, treatment and outcome assessment for OBPI. The process established a new network of opinion leaders and researchers for further guideline development, and multicentre research. The next step is to facilitate the implementation of the recommendations. / Thesis / Master of Science (MSc)