One way for early childhood professionals to progress in their professional development is by receiving the proper education from a specialized training program that focuses on how to effectively address young children’s emotional and behavioral needs. The Early Childhood-Social Emotional Behavior Regulation Intervention Specialists (ECSEBRIS) certificate program provides early childhood professionals with graduate-level education, practical experiences, and reflective supervision that teaches the necessary skills to become a sensitive and responsive educator when addressing the socio-emotional and behavioral challenges displayed by children zero to five-years-old. The overarching goal of this study was to examine whether the EC-SEBRIS certificate program trained early childhood professionals to be more sensitive and positively responsive to young children’s emotional and behavioral expressions. This observational study utilized a longitudinal explanatory, mixed-method research design. Quantitative analyses were used to describe data and compare differences between the pre- and post-program observations. Qualitative narratives were used to explain and extend the quantitative findings. This study used a contingent responding coding system to measure both children’s emotional and behavioral expressions and the responses that the EC-SEBRIS trainees used to address children’s emotional and behavioral expressions. This study found that the participants in the program demonstrated more positive and less negative responses to children's emotional and behavioral expressions over the course of the program. Specifically, trainees used significantly more supportive emotion socialization practices (e.g. direct-teaching and encouragement) when addressing children’s expressions of emotions and behaviors at the end of the program compared to the beginning of the program. Children who received directteaching as a response to their negative emotional expressions were more inclined to actively listen (e.g. made eye contact, acknowledged what was taught, etc.) to the trainees’ teachings of emotions and expressed their emotions and behaviors in a calm, effective manner. This study suggested that the EC-SEBRIS certificate program had the potential to promote professional development by training early childhood professionals how to positively address young children’s social-emotional development.