While the significance of principals' roles is widely recognized, and the impactful behaviors of principals are empirically delineated, little is known about whether principals spend time in an impactful way, whether principals' time use varies across different school contexts, or whether principals' time use is related to critical school conditions and outcomes such as school climate and student outcomes. We made an attempt to respond to these questions by conducting a secondary analysis of Trends in International Mathematics and Science Study data. We found that American middle school principals' job continues to be administration-bound, spontaneous and fragmented. In general, American principals could be classified into two major clusters: Eclectic Principals versus Balanced Principals. Higher school poverty, higher concentration of English language learners and more urbanity were associated with a higher incidence of Eclectic Principals. Nevertheless, except for teacher engagement, schools led by different clusters of principals did not differ in terms of parent/student engagement or student behavior. Although schools led by Balanced Principals tend to outperform those led by Eclectic Principals, this achievement difference was not statistically significant at 0.05 level. With a large national representative sample, the study fills knowledge gaps associated with small samples and limited attention to situational determinants of principal leadership activity.