This study replicates VanPatten and Cadierno (1993) in an attempt to determine whether or not explicit information given to learners receiving processing instruction is responsible for the beneficial effects of instruction. Fifty-nine subjects were divided into three groups: (1) one receiving processing instruction in object pronouns and word order in Spanish as in VanPatten and Cadierno (1993), (2) another receiving explanation only with no activities or practice, (3) and another receiving only the structured input activities with no explanation. A pretest/posttest assessment was used involving two tests, an interpretation test and a sentence-level production test. Results showed that the beneficial effects of instruction were due to the structured input activities and not to the explicit information (explanation) provided to learners.For some time, the language teaching profession has been exploring the role of formal instruction in grammar (for overviews, see, e.g., Ellis, 1990; Larsen-Freeman & Long, 1991, chap. 8; June 1993 issue of Studies in Second Language Learning, 15: 2). One particular focus of the discussion surrounding formal instruction has been the contribution that explicit information provides in the acquisition process. By explicit information, we mean explanation about properties of language provided by We would like to thank the Research Board of the University of Illinois for its financial support in conducting the present study. We would also like to thank the various anonymous reviewers who made important comments on an earlier version of this paper.