This study comprehensively and empirically examined a hypothesized model that incorporates the task model (i.e., planning and revision), documents model (i.e., intertext and integrated mental models), consideration of counterarguments as predictive variables, and text quality of essays as the dependent variable. Data were collected from 421 South Korean high school students who wrote argumentative essays using multiple documents and responded to a series of questionnaires measuring processing variables. Structural equation models were applied to analyze the data. The results indicated that the documents model predicted the participants’ text quality, while the effect of the task model was mediated by the documents model and consideration of counterargument. Notably, the paths in which planning and revision affect text quality are different. Furthermore, the intertext model and consideration of counterarguments, as opposed to the mental model, did not directly affect text quality. These findings not only contribute to the literature on multipledocument processing but also provide empirical evidence to suggest an interdisciplinary approach applicable in both language arts and content subject domains.