This series consists of two levels: A fondo, Nivel avanzado (Advanced level) and A fondo, Nivel superior (Higher level). These levels are equivalent to the B2 and C1 levels of the Common European Framework of Reference. Each level contains nine lessons, structured around a thematic core that deals with subjects such as emigration, the labor world, the radio, the environment, etc. The written and oral materials are original and come from news released by the press. Each unit is divided into three sections: grammar, vocabulary and functions. Students will work on oral and written comprehension and expression. The authors have also focused on sociocultural and sociolinguistic aspects of the language. In addition, there is a revision section every three units and another one to encourage learners to read literary texts.