In 2013, the NYC Leadership Academy (NYCLA) developed a leadership intervention--the Targeted Intensive School Support (TISS) program--in collaboration with the New York City Department of Education (NYC DOE) to support schools that were facing particular challenges. NYCLA asked the RAND Corporation to provide an independent evaluation of the program's implementation and effects, and those findings are detailed in this report. The TISS program consisted of five key components: (1) teaming and collaborative training in aligned preservice preparation programs for a principal and assistant principal (AP); (2) coplacement of a principal and AP into an NYC DOE school; (3) team-based coaching to support the principal and AP; (4) 328 hours of extended coaching over the first three years after placement; and (5) use of a diagnostic process to guide goal setting and coaching according to school needs. Implementation findings suggest that only two of the five key components were implemented with fidelity. A propensity weighting approach was used to compare schools with TISS principals to other schools with new principals trained through residency-based preservice programs who did not participate in TISS. Findings suggest no statistically significant differences between TISS schools and comparison schools on measures of student achievement, school culture, and principal retention. TISS schools underperformed relative to comparison schools on the measure of chronic student absenteeism. [Sponsored by NYC Leadership Academy through a subgrant from the U.S. Department of Education.]