INTRODUCTION: In 2005, the International Patient Decision Aid Standards (IPDAS) collaboration identified guidance and decision coaching as important dimensions of patient decision aids (PtDAs) and developed a set of quality criteria. We sought to update definitions, theoretical rationale, and evidence for guidance and/or decision coaching used within or alongside PtDAs for the IPDAS update 2.0. METHODS: We conducted 2 scoping reviews on guidance and decision coaching, including systematic searches and a hand search of the Cochrane Review on PtDAs. Eligible studies were randomized controlled trials (RCTs) on guidance or decision coaching used with/alongside PtDAs. Data, including conceptual models, were summarized narratively and with meta-analyses when appropriate. RESULTS: Of 1022 citations, we found no RCTs that evaluated guidance in PtDAs. The 2013 definition for guidance was endorsed, and we made minimal changes to the description of guidance. Of 3039 citations, we identified 21 RCTs on decision coaching informed by 5 conceptual models stating that people exposed to decision coaching are more likely to progress in making informed decisions consistent with their values. Compared to usual care, decision coaching with PtDAs led to improved knowledge mean difference [MD], 19.5/100; 95% confidence interval [CI], 10.0-29.0; 5 RCTs). Compared to decision coaching alone, PtDAs led to a small improvement in knowledge (MD, 3.6/100; 95% CI, 1.0-6.3; 3 RCTs). There were variable effects on other outcomes. We simplified the decision coaching definition slightly and defined minimal decision coaching elements. CONCLUSION: We found no evidence on which to propose changes in guidance in IPDAS. Decision coaching is continuing to be used alongside PtDAs, but there is inadequate evidence on the added effectiveness compared to PtDAs alone. The decision coaching definition was updated with minimal elements.