Understanding student performance in Algebra I is important because this course serves as the gateway to advanced coursework in mathematics and science through the remainder of high school and into postsecondary education. In the current study, we analyzed secondary data to evaluate the relationship between selected indicators of mathematics and the Algebra I performance of academically able and gifted learners who participated in above-level talent search testing. We used structural equation modeling to examine the relationship among selected variables and students' scores on a standardized measure of Algebra I achievement. Variables included prior mathematics ability, parental education level, whether a student was identified as gifted, participation in afterschool activities, the time spent on homework, and the amount of class time spent on discussions and lectures. Results indicate the strongest relationships were between mathematics reasoning and Algebra I achievement. Although gifted status was a strong predictor of mathematics reasoning, it was not strongly related to Algebra achievement, which supports the need for differentiated instruction for gifted learners. The amount of class time spent on discussion had a significant effect on the amount of time spent weekly on Algebra I homework. Rather than reliance on traditional lecture-based instruction, teachers should consider incorporating more classroom discussion on mathematical topics. (Contains 5 tables and 3 figures.)