This is an experimental study on the relative effects of Van Patten's Processing Instruction (PI) (1996, 2002), a "psycholinguistically-motivated" intervention in teaching second-language (L2) grammar, on young-adult Filipino learners of English. A growing body of research on this methodological alternative, which establishes form-meaning connection via processing of linguistic input leading to the L2 learner's developing system, has shown its superiority over the precedent long-held approach to grammar teaching. Traditionally, grammar instruction is "output-oriented", that is, students are instantly tasked to produce morpho-syntactic and/or lexical items through language drills. However, the use of the present perfect aspect in English, for one, is still a persistent error among Filipinos, even at the tertiary level, as evidenced in the results of college entrance examinations and teachers' formative and summative assessments. Two groups of sophomore students--a Processing Instruction (PI) group (experimental) and a traditional instruction (TI) group (control)--enrolled in a coeducational private university in Manila, Philippines, served as subjects of the study. These groups were pre-tested prior to the instructional treatment of the English present perfect: PI to the experimental group and production-based lessons to the TI group. A post test was administered, from which the scores obtained by the subjects were then statistically analyzed using Paired-Samples and Independent Samples T tests. Results reveal significant gains in post production and delayed production tests for both the TI and PI groups and in delayed interpretation for PI group only. Furthermore, results indicate that the PI group performed better than the TI group in all the three tasks mentioned. These results suggest the superiority of PI over TI.