One of the most controversial topics in Applied Linguistics is the role of learners' metalinguistic knowledge (MK) in second language (L2) learning and teaching. There seems to be no agreement between those who propose that MK is essential for L2 learning and those who believe that it can even be detrimental for L2 acquisition.Additionally, the subjunctive has been reported to be one of the most difficult structures to master for L2 learners of Spanish. It has been suggested that the subjunctive is acquired fairly late in an acquisition hierarchy of Spanish grammar and that, as a consequence, learners must reach a stage where they can produce syntactically sophisticated utterances in order to be "ready" for acquisition.Taking an Information Processing (IP) approach to language learning as a framework, this dissertation investigates the relationship between MK and grammatical accuracy by learners of Spanish at beginning, intermediate, and advanced levels of proficiency. Their MK is assessed through a set of terminology and grammaticality judgment tasks. Their mastery of the Spanish subjunctive is evaluated through a set of receptive and productive tests involving different subordinate clauses.The three groups of participants are compared with respect to their MK and their mastery of the subjunctive, and it is examined whether MK correlates with mastery of the subjunctive. Findings include: 1) an improvement on both subjunctive accuracy and terminology knowledge across levels; 2) a positive correlation between English MK and Spanish MK; 3) a positive correlation between MK and accuracy in the use of the subjunctive; and 4) agreement between the learners' acquisition hierarchy within the subjunctive and teaching order of subjunctive substructures.The findings show that MK has a positive impact on the mastery of this "difficult" structure. They are also consistent with other experimental studies that suggest that explicit instruction has a positive impact on L2 learning. The late and uneven acquisition of the subjunctive demonstrated by the subjects in this study also suports the hypothesis that there are "many subjunctives" to learn and that learners will not acquire this structure until they are developmentally ready (third year of instruction).

In a description of language, Ellis (1994) claims that "the bedrock of L2 is its vocabulary" (p. 11); while for Lewis (1993), language consists of "grammaticalized lexis", not "lexicalized grammar", and Nation (2001) adds that attention to vocabulary is unavoidable. This status of vocabulary determines its pervasiveness and implies the need for attention as claimed by Meara (1980). In second and foreign language teaching and learning, instruction is an important contributor in the development and consolidation of vocabulary knowledge while Computer-Assisted Language Learning has been described as facilitative in mediating instruction and improving learner independence (Chapelle 1998, 2001; Warschauer, 1998).The present study investigates narrative comprehension, immediate and delayed vocabulary retention as a result of implicit and explicit teaching and learning of vocabulary (Hunt & Beglar, 2005), with a hypertext reading task. Many researchers support that enhanced vocabulary activities and reading for meaning affect vocabulary acquisition (Krashen, 1989, Zahar et al., 2001; Paribakht & Wesche, 1997; Lee & VanPatten, 2003). For others, the degree of involvement in the processing and the noticed properties of words determine the degree of retention (Groot, 2000; Smith, 2004).Seventy-eight fourth-semester students of French as a foreign language from six classes at an American university participated in the study. They were randomly assigned to either the implicit or the explicit conditions, and received differential treatments. The subjects read the same enhanced electronic text with permanently highlighted target items in the explicit condition, and temporarily highlighted target items in the implicit condition. The target items were hyperlinked to the same textual, auditory, and graphic enhancements. The study also makes an overview of the effect of the motivation type on the subjects' performance levels.The statistical analyses reveal both strengths and weaknesses in the two modalities with regards to immediate and delayed retention; as one of the modalities favors immediate gain and the other longer-term retention. It is thus suggested that both modalities can be jointly implemented in a Computer-Assisted Teaching and Learning condition in order to achieve higher learning outcomes. The combination may favor the dual improvement in gain and retention in the learning process.

The communicative approach to language learning is widely taught in Western education, and yet its predecessor, the grammar-translation method, is still commonly employed in other parts of the world. In Sweden, the increasing popularity of the communicative approach is often justified by the high level of students’ communicative skills (Öhman, 2013). At the same time, students’ written texts and speech contain many grammatical errors (Öhman, 2013). Consequently, being aware of their tendency to produce grammatical errors, some students express beliefs regarding both the explicit and implicit learning of grammar (Sawir, 2005; Boroujeni, 2012). The objective of this thesis is to gain more knowledge regarding students’ beliefs concerning the learning of English grammar at the upper secondary level, in Sweden. With this purpose a survey was conducted in two schools in Sweden, where 49 upper-secondary English students participated. Qualitative and quantitative methods were applied to process the collected data. Despite some difference in the participants’ ages, there were many similarities in their attitudes towards the teaching and learning of grammar. The results show that the participants in both schools believe that only by applying both, explicit and implicit methods, can they obtain a high level of language proficiency. The results of this study can help teachers in planning different activities that enhance the students’ knowledge of grammar.