This study explores the notion of reading-writing integration in an EFL college composition class by focusing on reading-for-writing practices that serve as a means to connect reading practices and written products. From the perspective of reading-writing integration, this paper examines the effects the reading-for-writing practices may have on proficiency in four aspects of writing (i.e., content knowledge, organization, writing fluency, and grammar and spelling) in the context of an EFL reading-to-writing class. A mixed method combining both the qualitative and quantitative approaches was used to analyze surveys, interviews with students, reading texts, and written products. The results show that group differences in improvement in writing was found to be significant for the content knowledge and organization categories, indicating reading-for-writing practices affected some aspects of composition over the course of study. Specifically, the students in the more integrative group practicing reading in connection to writing produced more written intermediate texts as input for their writing than did those in the less integrative group, helping to acquire writing proficiency in the content and organization aspects. However, a reading-writing interaction alone does not lead to the improvement in the writing fluency in a local level and grammar and spelling, suggesting the important role of writing instruction in these areas. This study argues that the reading-writing integration coupled with a traditional writing instruction should be viewed as an integral part of the teaching practices in EFL college composition classes.