A broad literature search was undertaken in order to identify as many studies as possible where a form of training or intervention was conducted, and leader efficacy measured. We specifically searched for this Boolean string (and their translation in French): (“leader efficacy” OR “leadership efficacy” OR “leader self-efficacy”) AND (“training” OR “intervention”). We aimed to find studies published in English and French mainly, although work in other languages was also considered were feasible. We included any work that included our combined search terms, setting no exclusion criteria in order to be as inclusive as possible and avoid missing relevant work. We started our search on Google Scholar, to find all work that cited the article by Quigley (2013) and work that cited Hannah et al. (2008). We then looked at relevant meta-analyses (i.e., Avolio et al., 2009; Lacarenza et al., 2017) to include the studies that were included in their meta-analyses. Then, we searched the most prominent databases (i.e., PsychInfo, Proquest, ERIC, and Medline), using a full text search.

We also sought to include theses and dissertations by searching Proquest Dissertations and Theses Global, based on a title and abstract search. We also searched national databases of countries and regions with theses and dissertations in French or English (i.e., Australian Education Index, PASCAL, Theses Canada). We then searched conference proceedings of relevant scholarly conferences (i.e., AIPTLF, AOM, ASAC, SIOP, EAWOP, SMA, WAM, EAM, Midwestern AOM, British AOM, African AOM, Asia AOM, European AOM, Australian and NZ AOM, Indian AOM).