Coaching is a key lever for supporting professional learning in early childhood, and coaches serve a critical role in the coaching process. However, little is known about coaches themselves which is a critical gap in evaluating the efficacy of coaching and for making decisions around coaching policies and practices. This mapping review synthesizes the early childhood coaching research to identify the background characteristics and training experiences of early childhood (0--8) coaches. We reviewed 374 studies for information about coaches and their experiences in early childhood coaching. "Research Findings:" Coaches were experienced and educated; however, qualification requirements varied across studies. Coaches were generally part of the research team that conducted the study. Over 15 different terms were used to describe coaching. Only 145 studies provided information about coach training, which tended to be via workshops and focused on implementing a specific coaching model. Overall, we noted inconsistency in reporting and the absence of information across studies. "Practice and Policy:" These findings are a call to action for researchers. More consistency and thoroughness is needed in reporting of coach-level characteristics as well as the coach training process. Additionally, there is a need for a consensus on the definition of key coaching terms.