Many English language learners (or "L2" students) in American colleges struggle to properly incorporate research into their academic writing. Like native-English speakers (or "L1" students), many L2 students use "patchwriting," a form of plagiarism in which phrases and sentences from outside sources are mixed with original language. This study measures the prevalence of patchwriting by first-year L2 students at Truman State University. Also, a survey of L2 students investigates cultural and developmental factors that may contribute to patchwriting. This study questions the assumption that L2 students know that their patchwriting is plagiarism, yet it also challenges the belief that cultural differences make them unaware of the rules for avoiding plagiarism. Drawing on current psychological research, studies of L1 writers, and literary theory, this thesis seeks to describe the typical challenges faced by L2 students, in order to inform effective pedagogy for research-based writing and appropriate plagiarism policy for institutions.