This book presents a state-of-the-art study of variation that considers meaning-in all its possible facets-as the key to scientific explanation. It brings together a group of international scholars whose work pursues the systematic integration of meaning and function in models of grammatical usage. After a foreword by the world-leading specialist Nikolas Coupland and a theoretical introduction by editors Miguel A. Aijon Oliva and Maria Jose Serrano, the seven empirical chapters focus on morphosyntactic phenomena in different varieties of Spanish, analyzing a wide range of discourse types and communicative domains, from sociolinguistic interviews to mass media and social network interactions. These studies offer a basis for the study of variation from similar viewpoints in other languages.