In this dissertation we examine the effects of pronunciation instruction on the perception of a novel L2 contrast. The novel contrast in this case is the glottal fricative which results in Spanish from the suppression buccal gestures of /s/ in the word-medial coda position. This process which occurs in Spanish, but not English is known as debuccalization although it has also been referred to as aspiration. It has been suggested in the SLA literature on the teaching of pronunciation that teaching pronunciation will improve listening comprehension, although it has rarely been examined empirically. The Flege's (1995) Speech Learning Model suggests that sounds in L2 are much more difficult t acquire when they are similar to sounds in L1 but that over time, they can be acquired through L2 input which helps learners to establish new L2 categories. In order to test whether pronunciation instruction, which we view as a form of targeted input, can positively affect the perception of a novel L2 contrast, we compare the perception of pairs of words, including some near minimal pairs with debuccalization, by a control group and two experimental groups. All participants in the study are native English speakers who are registered in intensive beginner classes at the University of Buffalo. All groups participate in perception tests at weeks one and five and the experimental groups receive pronunciation instruction and a third perception test at week three. The two experimental groups receive different types of pronunciation instruction: instruction in a classroom setting and in a laboratory setting. While pronunciation instruction does not lead to more accurate perception of the glottal fricative that results from debuccalization in this study, we suggest that in the future, this may be a possibility with a larger amount of input. [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.]