The philosophy of this best-selling introductory text is to emphasize communicative proficiency. Based on the Natural Approach, the text stresses the use of activities in a natural and spontaneous classroom atmosphere. In this comprehension-based approach, the development of receptive skills-listening and reading precede and form the basis for the development of the productive skills; speaking and writing. Dos Mundos is designed so that class time is devoted to exposing the student to Spanish through the abundant activities in the text, allowing the grammar explanations and exercises to be studied by the student outside of class.