Effective manager? Savvy politician? Heroic leader? School CEO? Reformers yearn for principals who can not only play these roles but also raise test scores and do so quickly. Many principals in different districts can earn thousands of dollars in bonuses for boosting student achievement. But the job of principal demands far more beyond gains in test scores. Principals are expected to maintain order, to be shrewd managers who squeeze a dollar out of every dime spent on the school, and astute politicians who can steer parents, teachers, and students in the same direction year after year. They are also expected to ensure that district curriculum standards are being taught, as well as lead instructional improvement that will translate into test score gains. I cannot forget that principals are caught smack in the middle between their district office bosses and teachers, parents, and students in each of their schools. Being a principal, then, is a tall order. As one New York City high school principal put it: “You’re a teacher, you’re Judge Judy, you’re a mother, you’re a father, you’re a pastor, you’re a therapist, you’re a nurse, you’re a social worker.” She took a breath and continued: “You’re a curriculum planner, you’re a data gatherer, you’re a budget scheduler, you’re a vision spreader.” Yet, at the end of the day, in the fourth decade of a school reform movement that began in the early 1980s, the pressures on principals remain and the lure of rewards for raising test scores and graduation rates, today’s measure of instructional leadership (e.g., promotion to the district office, a superintendency) persist. The research on gains in test scores across multiple years clearly points to the principal as the catalyst for instructional improvement. But being a catalyst does not identify which specific actions influence what teachers do or translate into improvements in teaching and student achievement. Principals set up and sustain a series of structures that help both teachers and students. Researchers have found that what matters most is the school climate in which principals’ actions occur. And that climate is built by the principal. For example, classroom visits, often called “walk-throughs,” are a popular vehicle for principals to observe what teachers are doing. Principals might walk into classrooms with a required checklist designed by the district and check off items, an approach likely to misfire with teachers. Or the principal might have emailed the teacher a short list of expected classroom practices created or adopted in collaboration with teachers in the context of specific school goals for achievement. The former signals the teacher “uh, uh, my principal is gonna evaluate me,” while the latter signals a context characterized by collaboration and trust within which an action by the principal is more likely to be influential than in a context of mistrust and fear. So research does not point to specific sure-fire actions that instructional leaders can take to change teacher behavior and improve student learning. Instead, what’s clear from studies of schools that do improve is that no single act by a principal but a cluster of factors account for improved students’ academic performance. Over the past forty years, then, researchers have listed factors associated with raising a school’s academic profile. They include: teachers’ consistent focus on academic standards and frequent assessment of student learning, a serious school-wide climate toward learning, district support, and parental participation. Recent research also points to the importance of mobilizing teachers and the community to move in the same direction, building trust among all the players, and especially creating working conditions that support teachers working together while expanding their knowledge and skills.