Under the premise that vocabulary learning in a Spanish as a second language in-class environment may be affected by the instructional approach adopted by the instructors or the materials followed, this study explores the influence of rather distant teaching styles, such as implicit and explicit approaches, on the learning outcome of Spanish lexicon. Research has shown successful results in studies undergoing both approaches (Ellis, 1994; Barcroft, 1994; Maura, 1995; Huckin and Coady, 1997; Schmitt, 2000; Paribakht and Wesche, 2000; Hiebert and Kamil, 2005). Despite the adopted instructional approach, vocabulary is finally assimilated by the learners to an extended degree. Nevertheless, explicit style shows better results in early stages of learning, whereas implicit style proves to be more effective in a more advanced stage of learning, since beginning students' lack of vocabulary limits their inferring ability (Zimmerman, 1997; Coady, 1997). The reason is that the explicit approach facilitates breadth knowledge of the material, in opposition to implicit approach, which facilitates a depth of knowledge (Paribakht & Wesche, 1996). As a result, we may have students with vocabulary breadth knowledge, who gloss a Spanish word in English, but are unable to apply or recognize the word in a context; as opposed to students with depth of knowledge, who may know the Spanish glosses of English words and their meaning variations depending on context. On the other hand, Second Language Acquisition (SLA) has also proved to be influenced by factors out of the scope of instructional techniques. Each learner may approach differently to the foreign language learning process and affect his/her final results (Oxford, 1990; Skehan, 1991). Facts such as motivation, or individual strategies, will influence the mastery of vocabulary regardless of the instructional approach. This study presents the vocabulary learning results of a long term implicit and explicit approach treatment applied to two different sections of an intermediate Spanish course. Lexicon learning results will be correlated with the individual factors of motivation and learning strategies to measure aspects that may be determinant in the acquisition of Spanish vocabulary in an in-class university-level setting. [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.]