High-quality early childhood education and care (ECEC) - particularly care defined by highly responsive interactions between educators and children - has the potential to have lasting positive impacts on children's development. While there is variability in the level of quality among early education and care settings, professional development for early childhood educators has been shown to be an effective means to improve both ECEC quality and child outcomes. As many professional development programs are time and resource intensive, we sought out to test the efficacy of a brief (5 hr) professional development program that included a workshop, individual coaching, video feedback and text messaging. "Research Findings:" Results of a cluster randomized controlled trial with 93 educators indicated that the program improved educators' responsivity three-months after intervention (d = 0.60, p = 0.035), but not classroom-wide levels of emotional support or instructional quality. Trend analysis revealed the greatest improvements occurred after the workshop and first coaching session and leveled off over time. "Practice or Policy:" Preliminary evidence suggests brief professional development programs may improve interaction quality with effect sizes comparable to those of longer programs. Well-powered studies using multiple arms or sequential randomization will help optimize the efficiency and effectiveness of professional development.