This study examines the power of cognitive and noncognitive variables to predict students' performance in algebra. We investigated students' prior year's assessment scores and demographic characteristics to predict eighth-grade algebra scores. Using California statewide assessment data, we explored predictive factors in three regression models. These analyses reveal that the seventh-grade mathematics test scores account for 61% of the variance in eighth graders' algebra test scores. Analyzing subscores of the seventh-grade mathematics test, the assessment content focus of "rational numbers" is a major predictor, contributing 48% of the variance in eighth graders' algebra test scores. On the other hand, students' demographic variables show little predictive power for eighth-grade algebra scores. This study provides empirical evidence for understanding the factors that impact a student's success in learning algebra.