Set in a freshman composition course using Blackboard for all assessments, this study considered aggregate data to investigate associations among formative assessment variables with the development of college writing skills. The study population was linguistically diverse students enrolled in a metropolitan community college in the Northeast United States. The research design employed a multivariate data analytic framework to examine associations among final class average, total user activity, total user activity in hours, and final quiz average as measures of formative assessment and college writing achievement. Results of Pearson correlation analysis indicated six significant associations among microengagement, formative assessment, and college writing achievement. The results suggest that repeatable online formative assessments are an effective way to increase student writing achievement, particularly in populations with widely varying abilities and inclined to struggle with college-level composition. Future research is needed to determine predictive relationships among these significant correlated pairs.