Students' engagement and performance in their first year of high school offer strong signals about their prospects for earning a diploma 4 years later. These performance measures can be used to construct "on-track" indicators to measure a school's performance and to identify needs of specific students who are at risk of dropping out. This article undertakes a systematic reanalysis of several on-track indicators that predicted the likelihood of graduating with a New York State Regents diploma in New York City. The analytic dataset contains comprehensive longitudinal information for first-time 9th graders who are enrolled in high school between 2001-2002 and 2010-2011. The results show that the current New York City Department of Education indicator (earning 10 or more course credits in the 9th grade) offers a reliable prediction of graduation with a Regents diploma. However, an indicator based on earning 10 or more credits and passing at least one Regents exam represents a substantial improvement on the current indicator and was used as the primary indicator for additional analyses. These analyses showed that this on-track indicator has been reliable and stable across seven cohorts of entering 9th graders. The analysis also shows that the substantial increase in 9th-grade on-track rates offers a reliable foreshadowing of increases in Regents diploma graduation rates in New York City. Additionally, the on-track indicator was highly predictive for a wide range of student subgroups and helps to highlight the prominent gaps in performance along racial, gender, and economic lines. Finally, the article highlights significant variation in on-track rates across schools, that should be investigated in future research. (Contains 7 tables, 5 figures, and 11 footnotes.)