Scaling up effective early childhood programs is a major policy challenge. This paper is one of the first to experimentally evaluate the impact of a low-cost home visiting program implemented at scale by a low-income country government (Nicaragua). We find that access to home visits has a modest positive impact on child development outcomes and behavior (0.11-0.15 standard deviations). Further, using a unique dataset of in-situ home visit observations, we find evidence for the importance of home visit quality. In communities where home visitors more effectively engaged caregivers, prepared for visits, and followed the curriculum, effects on child development were larger. We also compare different types of monitoring structures and find that when monitoring was locally-led (versus centralized), home visits were higher quality. Our findings provide novel evidence of a home visit program implemented at scale in a low-income country, emphasize the importance of quality, and show promise for the use of community-based monitoring strategies when scaling-up.