IMPORTANCE Parent-child interactions are critical for language development in early life. OBJECTIVE To test whether a clinic-based intervention was associated with improved home language environment and language development. DESIGN, SETTING, AND PARTICIPANTS A pre-post study of a multifaceted clinic-based intervention called Talk It Up was conducted for 61 English-or Spanish-speaking families with children aged 2 to 12 months. Enrollment took place at a single urban pediatric clinic from January to November 2017, with follow-up data collection through May 2018. Analyses took place from June to August 2018. INTERVENTIONS The 6-month multifaceted intervention consisted of delivering Language Environment Analysis word counts with clinician feedback, coaching, and twice-weekly pushes of brief instructional videos via a commercially available smartphone application. MAIN OUTCOMES AND MEASURES Baseline and follow-up z scores for adult word counts, parent-child conversational turns, and child vocalizations and language development as measured by the Developmental Snapshot score were compared and adjusted for confounders. RESULTS Among 61 families, the mean (SD) child's age at baseline was 5.9 (3.3) months. English was the primary language spoken in the home for 54 families (89%). At follow-up, Talk It Up was associated with significant improvements in adult word counts (mean z score, 0.30; 95% CI, 0.05-0.55), parent-child conversational turns (mean z score, 0.29; 95% CI, 0.002-0.59), and Developmental Snapshot score (mean, 6.59; 95% CI, 0.95-12.23), but there were no improvements in child vocalizations (mean z score, -0.13; 95% CI, -0.49 to 0.24). CONCLUSIONS AND RELEVANCE A multifaceted clinic-based approach to promote parent-child interactions holds some promise. Future, larger studies are warranted.