We investigated Early Head Start home visitors' use of evidence-based practices and the effectiveness of a web-based system to support these practices. Home visitors learned to use 3 evidence-based practices: (a) frequent assessment of children's early communication for screening and progress monitoring, (b) 2 home-based language promoting interventions, and (c) data-based decision making in the use of the language promoting intervention strategies. We randomly assigned 1 group of home visitors to use an online data collection system and receive training in data-based intervention decision making and in the evidenced-based language interventions. The other home visitors had access to these tools and trainings, but in addition, they had web-based support (Making Online Decisions; MOD) linked to the children's expressive communication data. We found that the expressive communication of children served by home visitors who used the MOD grew significantly more than children whose home visitors did not have MOD support. Home visitors who used the MOD reported high satisfaction with its use. Future research and implications for early intervention and home visiting practices are discussed. (Contains 2 figures.)