The problem of poor writing skills at the postsecondary level is a large and troubling one. This study investigated the writing skills of low-skilled adults attending college developmental education courses by determining whether variables from an automated scoring system were predictive of human scores on writing quality rubrics. The human-scored measures were a holistic quality rating for a persuasive essay and an analytic quality score for a written summary. Both writing samples were based on text on psychology and sociology topics related to content taught at the introductory undergraduate level. The study is a modified replication of McNamara et al. ("Written Communication," 27(1), 57-86 2010), who identified several Coh-Metrix variables from five linguistic classes that reliably predicted group membership (high versus low proficiency) using human quality scores on persuasive essays written by average-achieving college students. When discriminant analyses and ANOVAs failed to replicate the McNamara et al. ("Written Communication," 27(1), 57-86 2010) findings, the current study proceeded to analyze all of the variables in the five Coh-Metrix classes. This larger analysis identified 10 variables that predicted human-scored writing proficiency. Essay and summary scores were predicted by different automated variables. Implications for instruction and future use of automated scoring to understand the writing of low-skilled adults are discussed.