How can a dedicated principal work really, really hard but fail to get significant gains in student achievement? The answer is obvious: by spending too much time on the wrong things and not enough on the right things. The principal's number-one priority is zeroing in on the highest-priority activities for bringing all students to high levels of achievement. If principals don't put the two or three top priorities into their calendar first, all the other stuff will clutter their days. For the principal, the big rocks are the actions that drive high achievement for all students. Without a clear sense of these research-based activities, a school leader will accomplish very little. Robert Marzano, Mike Schmoker, Douglas Reeves, Richard DuFour, Ronald Ferguson, and others have given principals a much clearer idea of what those activities are. The challenge is figuring out which two or three are the highest priority in their school, setting measurable goals, and pursuing them with laserlike determination. Once they have put their lean, mean strategic plan in place, it's much easier to say no to off-mission activities, to be present for students and staff members, and to roll with the punches (because there will still be those crazy days).