Since Swain's (1985) Output Hypothesis, producing output in second language (L2) has been assumed to be a crucial cognitive process that promotes L2 acquisition, by actively facilitating various cognitive processes (e.g., noticing, hypothesis testing, conscious reflections of own language use, and automatization of the linguistic knowledge) (de Bot, 1998, Gass, 1997; Izumi, 2003; Muranoi, 2007a; Swain, 1985, 2005). In particular, the noticing function of output has been widely accepted as a cognitive rationale of L2 learning in Second Language Acquisition (SLA)/Instructed SLA (ISLA). Despite the commonly accepted Swain's Output Hypothesis and the noticing-inducing function of output, previous empirical studies that investigated whether and how producing L2 output could induce various types of learner-noticing and impact overall grammar learning gains have reported mixed results. Therefore, this study investigated how producing L2 output could induce learner noticing in a subsequent input (i.e., output-induced noticing) and contribute to the learning of the English past counterfactual/hypothetical conditional through a hybrid design of both product- and process-oriented research approaches. The participants of the study were 117 international undergraduate and graduate students in the U.S. They were assigned to one of the three conditions (Oral Output, Written Output, and Input-Only Comparison Groups) and then engaged in each treatment task, respectively. During the treatment sessions, all the learners followed the same four instructional steps: (1) listened to an oral introduction that provided background knowledge of a reading text; (2) read a short text (First Input); (3) engaged in each different treatment task (Oral Output, Written Output, or Aural Input); and (4) read the same text again (i.e., subsequent input) (Second Input). Both output groups engaged in the same text-reconstruction task, in which they were asked to reconstruct the text that they had just comprehended as accurately as possible using descriptive picture cues. However, the modality of the reconstruction was different (an oral or a written mode). The Input-Only Group listened to a text narration while watching the same descriptive picture cues. During the first and second input, learners' noticing behaviors on the target form were measured through an online, objective measure (i.e., eye-tracking) with two different levels of processing (i.e., the early [first-pass reading time, FPRT and the late measures [re-reading time, RRT]). In addition to these two process-oriented measures, the learners' overall learning gains were also assessed through a written-picture description test (WPDT) and an oral elicited imitation test (OEIT) in a pretest and posttest design as product-oriented measures. Overall, the results of the study revealed that producing L2 output as a form of text-reconstruction induced learner noticing, which was evidenced by both Oral and Written Output groups' significantly increased eye-fixation duration to process the features of the target grammatical form in the subsequent input, whereas the Input Only group showed significantly decreased eye-fixation duration to process the form. The degree of output-induced noticing was moderated by the modality of output and the levels of the eye-tracking (FPRT or RRT). The results of the late measure of eye-tracking (i.e., RRT) indicated similar eye-fixation duration gains from the first reading to the second reading for both groups, but the results of the early measure (i.e., FPRT) showed a significantly higher FPRT for the Written Output group but not for the Oral Output group. As for the impact of L2 output on the acquisition of the target form, however, the grammar test results did not show any significant group differences, even though slight differences were indicated in the descriptive results. Therefore, the findings of the study did not indicate measurable effects of L2 output on grammar learning but the eye-tracking results demonstrated the detailed mechanisms of how the noticing-triggering function of output was promoted in the subsequent input after engaging in L2 output practice. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]