Each school should have a well-prepared principal capable of improving student performance. While principal preparation advocates identify important program features (e.g., extended internships), few studies assess the impact of placing new principals trained by programs exhibiting these features on student learning. Using comparative interrupted time series, our study examines impact of placing new principals trained by four preparation programs identified as having promising preparation program features on student achievement, using student-level data for six school years. We find little evidence that inexperienced principals from the four programs increased student achievement more than inexperienced principals trained by other programs. We also find significant variation in school's student performance among inexperienced principals within the programs of interest.