Regression analysis is a method that analyzes the variability in the dependent variable based on a change in one or more of the independent variables. The analysis can be useful in selecting variables that might be influential in language acquisition or as a tool to predict language learning outcomes. In this chapter, a confirmatory approach to the prediction of English language achievement is used within the framework of regression analysis. A dataset pertaining to English language learners (ELLs) is analyzed within the theoretical regression framework to validate the significance of variables in the explanation and prediction of ELLs’ performance on an English language arts (ELA) examination. The consequence of violating assumptions required in performing regression analysis is also examined. Graphs and SAS codes are provided throughout the chapter for practitioners’ use.