Summarization and persuasive writing are important in postsecondary education and often require the use of source text. However, students entering college with low literacy skills often find this type of writing difficult. The present study compared predictors of performance on text-based summarization and persuasive writing in a sample of low-skilled adult students enrolled in college developmental education courses. The predictors were general reading and writing ability, self-efficacy, and teacher judgments. Both genre-specific and general dependent variables were used. A series of hierarchical regressions modeling participants' writing skills found that writing ability and self-efficacy were predictive of the proportion of functional elements in the persuasive essays, reading ability predicted the proportion of main ideas from source text in the summaries, and teacher judgments were predictive of vocabulary usage. General reading and writing skills predicted written summarization and persuasive writing differently; the data showed relationships between general reading comprehension and text-based summarization on one hand, and between general writing skills and persuasive essay writing on the other.