Following an initial investigation (Izumi, Bigelow, Fujiwara, & Fearnow, 1999), this study examines the noticing function of output (Swain, 1995, 1998), namely, the activity of producing the target language that may prompt L2 learners to recognize their linguistic problems and bring relevant aspects of the L2 to their attention. Before completing (a) essay-writing tasks and (b) text reconstruction tasks, two groups of ESL learners received the same input containing numerous examples of the target form, the past hypothetical conditional in English. One group was given opportunities for output whereas the other group engaged in comprehension-based activities. Although the results indicate no unique effects of output, extended opportunities to produce output and receive relevant input were found to be crucial in improving learners' use of the grammatical structure. A closer examination of the data suggested, however, that output did not always succeed in drawing the learners' attention to the target form, a phenomenon that seems related to both learner and linguistic factors. The essay-writing tasks were found to be much more susceptible to such individual variation than were the text reconstruction tasks. Further research is necessary to more precisely specify the noticing function of output and derive effective uses of output in L2 teaching.