Purpose: This study tests key constructs of sociocultural and organizational learning theories with quantitative methods to better understand the nature and impact of district and school leadership and actions on the quality of programs of family and community involvement. Research Design: Survey data from a "nested" sample of 24 districts and 407 schools are used to measure theoretical constructs of district "assistance" to schools and "shared work" on partnership program development. Hierarchical linear modeling (HLM) analyses explore the independent and simultaneous contributions of district leadership and school teamwork on the implementation of basic structures and advanced outreach in partnership programs. Also, gap analyses compare supplementary data from 220 schools that had consistent district leadership for 3 years to 106 schools without this support. Findings: HLM analyses show that principals' support for family and community involvement and schools' reports of district assistance contribute significantly to schools' basic program implementation and to advanced outreach to involve all families in their children's education. Over and above school measures, district leaders' direct facilitation contributes to the quality of the school programs. Gap analyses indicate that schools with consistent district leadership take more basic and advanced actions to establish and improve their partnership programs. Conclusions: This study--with a large sample of districts and schools, appropriate quantitative methods, and a content focus on partnerships--provides strong empirical support for the importance of sociocultural and organizational theories in studying school improvement. Implications for improving district and school policy and practice are discussed. (Contains 4 figures, 2 tables, and 5 notes.)