© 2015 Elsevier Inc. Background: Current methods for teaching and assessing competencies that characterize expert intraoperative performance are inconsistent, subjective, and lack standardization. This mixed-methods study was designed to define and establish expert consensus on the most important competencies required to perform a thyroidectomy safely. Methods: Cognitive task analyses for thyroidectomy were performed with semistructured interviews of experts in thyroid surgery. Verbal data were transcribed verbatim, coded, and categorized according to themes that were synthesized into a list of items. Once qualitative data reached saturation, 26 experts were invited to complete 2-round online Delphi surveys to rank each item on a Likert scale of importance (1-7). Consensus was predefined as a Cronbach's α ≥ 0.80. Results: Sixty items were synthesized from 5 interviews and categorized into 8 sections: preparation (n = 8), incision/exposure (n = 11), general considerations (n = 4), middle thyroid vein (n = 1), superior pole (n = 5), inferior pole (n = 5), posterolateral dissection (n = 19), and closure (n = 7). Eighteen (69%) experts from 3 countries participated in the Delphi survey. Consensus was achieved after 2 voting rounds (Cronbach's α = 0.95). Greatest weighted sections included "Superior Pole Dissection" and "Posterolateral Dissection.". Conclusion: Consensus was achieved on defining the most important competencies for safe thyroidectomy. This blueprint serves as the basis for instructional design and objective assessment tools to evaluate performance.