This investigation focused on the quality of parent–provider relationships in a Part C early intervention program. An observational coding system was developed as an exploratory tool to describe aspects of the parent–provider relationship over a 1-year period. In particular, we were interested in the extent to which the quality of the parent–provider relationship was related to maternal responsivity and children's social–emotional functioning. Participants included toddlers with developmental disabilities, aged 11–36 months, their mothers (n = 37), and their early intervention practitioners (n = 29). Observational coding was conducted at 3 intervals, with initial evidence supporting the use of the observational coding system. Composite scores of relationship quality were not significantly associated with parent or child outcomes, but more dynamic measures were. More specifically, attunement between the parent and provider on dimensions such as warmth and positive regard was associated with fewer child-internalizing behaviors. Change in mother behavior over time was related to higher levels of maternal responsivity. Findings are discussed in terms of the importance of examining the dynamic and transactional nature of parent–provider interactions over the course of an intervention.