One of the most controversial debates in the history of first and second language learning is the role of grammar and grammar teaching. The discussion has not ended yet. The present study focuses on the grammar of Spanish as a second language. Several old and new aspects about classical questions are analysed: ‘What is grammar?’ ‘What is teaching grammar?’ ‘Should we teach grammar at all? ’ ‘What kind of grammar should be taught? ’ ‘Why, how and when are we supposed to teach it? ’ ‘Is there a relationship between the teaching of grammar and the use of the language?’ ‘Which is the role of grammatical reflection in teaching grammar and in teaching second languages?’ Our belief is that, in the field of second language learning, grammar is crucial not only as an instrumental tool but also as a conceptual knowledge. A pedagogical grammar can contribute to interlanguage development and can enhance autonomous learning and critical thinking. The last chapter focuses on how to apply a wiki platform to create collaborative environments which enable a grammar learning and teaching model based on translation, metalinguistic awareness and grammatical reflection experiences.