Resulting from a fragmented landscape of policies for and uneven investments in the early childhood education (ECE) field in the United States, the qualifications of the ECE teaching workforce are typically quite low. This article first reviews the history and status of the ECE teaching workforce in the United States, focusing on the evolution of the field, current demographic characteristics of the teaching workforce and the pathways to professional development and professional preparation of the teaching workforce. The authors then discuss the legacies of this history and policy landscape: a lack of quality, equity and sustainability. Offering a re-conceptualization of professional development within the context of systems thinking, the article concludes with a discussion of innovations and challenges with which the field contends relative to workforce development. (author abstract)