Most validity studies of ISLLC standards and indicators rely heavily on focus groups and perceptual surveys. This study included self-report and observational data on principals' use of time. A content analysis tested ISLLC's descriptions of instructional leadership with a related set of Kentucky's Standards and Indicators for School Improvement (SISI) as well as across the observational job analyses of two sets of principals: (a) five elementary and secondary principals in a typical rural district and (b) five matched for school characteristics from high performing schools on Kentucky's assessment system. Results reinforce early studies revealing the intense and fragmented nature of principals' work, but results question whether ISLLC provides sufficient guidance for principals' instructional leadership performance as compared to Kentucky's SISI. ISLLC seems to offer better descriptions of legal and ethical standards as well as guidance on building community internally and externally to the school; however, ISLLC is silent about principals' interactions with students. (Contains 6 tables and 2 figures.)