This thesis aims to investigate some linguistic problems that arise in the process of learning Portuguese as a foreign language. Several difficulties can be detected in the phonetic, morphosyntactic, semantic and pragmatic fields, which I will attempt to highlight. Among these there is one that attracts more attention because it represents an extensive part of the acquisition of any language: the use of verbs, especially the subjunctive. The process of learning different Portuguese verb endings is the main problem when the student is a native English speaker, since the English subjunctive is only noticeable in certain forms and tenses. After defining these and related problems, my thesis will suggest methods to overcome the difficulties that students face in learning the Portuguese subjunctive and will address the questions: How should this aspect of grammar be presented to learners in an effective way? Which communicative tasks should be selected and developed? Which aspects of the input would acquirers need in order to undertake these tasks? What learning strategies should be incorporated to improve communicative competence?