The current study investigated the effectiveness of large-scale, state-sponsored language and literacy professional development (PD) intended to improve early childhood educators' knowledge, beliefs, and practices. PD was offered in a real-world context and delivered at-scale across the state, implemented by an independent contractor. Educators (n = 535) were randomly assigned to participate in one of three types of PD: 30 hrs of language and literacy PD presented in a workshop format, 30 hrs of language and literacy PD plus monthly coaching, or PD on alternative topics (comparison). Baseline and outcome measures were collected by an independent research team to determine PD effectiveness. Growth curve analyses showed little change in educator outcomes over an 18-month period, with no differences among conditions or evidence of moderation by educator or classroom characteristics. Explanations for lack of PD impacts and the importance of evaluating educational investments are discussed. (author abstract)