This dissertation examines the linguistic and extralinguistic factors that influence changes in performance in second language speech perception and speech production experienced by study-abroad returnees in the first nine months after the end of the study-abroad program. English-French bilinguals who had recently returned from a four-month study abroad program in France participated in two speech perception and two speech production experiments at three points in time after their return home from the study-abroad stay (two, five, and nine months after their return). Two groups of native French speakers and native English speakers served as controls. A number of linguistic and extralinguistic factors were investigated with regards to their influence on performance changes across time. The experiments revealed that bilinguals not only did not show signs of language attrition, but rather they retained their skills for all tasks across the first five to nine months after their return from France, and for some tasks (AX discrimination, lexical decision, picture naming) they even improved their performance across time. This was true for bilinguals who were still taking French classes, and even for those that were not taking classes and reported low overall exposure to French. In addition, it was shown that initial proficiency did not affect the amount of improvement across time, while amount of exposure made a difference in the phonological perceptual task (AX discrimination). Furthermore, highly motivated bilinguals with a positive attitude towards the French culture were shown to improve more across time than less motivated bilinguals. Finally, high executive functioning was shown to lead to bigger improvements across time. These results are important at a theoretical level, since they provide the possibility to extend second language speech acquisition models and can inform a multi-componential model of language attrition, which includes linguistic as well as extralinguistic factors for language changes across time. Furthermore, the results have practical implications, in that they can help language instructors and students identify which linguistic and behavioral factors to focus on in the language learning environment to aid in the long-term retention of second language skills. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]