Community development partnerships for youths offer valuable resources for school improvement. Unfortunately, these resources may not be tapped because school leaders have not been prepared to understand these partnerships. The evaluative research reported partnership-related understanding, aiming to prepare leaders to contribute to, and benefit from, partnerships. This research employed case study methodology to derive theories of change from five successful youth development partnerships. These partnerships' theories of change provide action-oriented knowledge for scale-up in other school communities. Among this research's other contributions are partnership commonalities, indicators of uniqueness, and partnership classifications. Differences between adult-led and youth-led partnerships are especially salient. Expanded improvement planning may incorporate youth leadership and capitalize on resources provided by partnerships. (Contains 9 figures and 1 note.)