As part of the Dynamic Model of Multilingualism (DMM), Herdina & Jessner (2002) cite multilinguals' increased metalinguistic awareness as one of the key factors that distinguish third language acquisition from second language acquisition. Many TLA studies have sought to show that this increased metalinguistic awareness and the beneficial effects that it has on L3 language learning is related to the number of languages known by an individual. The current study, however, questions whether multiple language-learning experiences alone are enough to influence metalinguistic awareness and L3 learning ability and investigates the role of L2 proficiency. Similar to Cummins' (1976) threshold hypothesis with regard to the relationship between degree of bilingualism and metalinguistic awareness, the current study seeks to determine whether some threshold level of proficiency must be achieved in at least one of an individual's second languages before the benefits of increased metalinguistic awareness as they relate to L3 learning can be observed. In order to investigate the relationship between language proficiency, metalinguistic awareness, and subsequent language learning ability; the current study examines the performance of university students at low versus high L2 proficiency on tests of German language attainment after approximately 45 minutes of interactive, communicative online instruction in German as a third language. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]