With increased demand for improved early childhood education services, it is important to better understand the essential professional development resources that have the greatest impact on both teacher and child outcomes. This study compared the effectiveness of two teacher-training models in bilingual Migrant and Seasonal Head Start and Head Start classrooms. Both conditions included the use of a technology-based student progress-monitoring tool. The progress monitoring provided detailed feedback on students' progress 15 across the academic year and helped organize instructional groupings. The comprehensive treatment condition included biweekly professional development sessions, in-class mentoring, and provision of classroom materials, whereas the treatment- control condition included only the provision of a limited set of classroom materials. Across multiple sites in Texas, 49 pretest and posttest teacher observations and bilingual child assessments were collected on a subsample of students (n = 387). Research Findings: Improvements in teaching behaviors were observed in both experimental conditions; no significant differences were observed between teachers across conditions. Three measures of child language and literacy growth differed significantly, favoring the comprehensive treatment model, but most outcomes did not differ significantly between groups. Practice or Policy: Implications of these mixed findings and future research directions are discussed. (author abstract)