The book offers a compilation of recent linguistic research on Ecuadorian Spanish based on synchronic and diachronic data. Ecuadorian Spanish studies are scarce or are scattered across time and space, and there is no systematic account of what has been done so far. Ecuadorian varieties of Spanish, especially those spoken in the highland regions, have existed in a long-term contact situation with different indigenous languages. This book offers a glimpse of varieties spoken all along the Andes, as well as some varieties spoken in the Amazonian region. It draws on methodologies used in variationist sociolinguistics, discourse analysis, and geolinguistics. Its key findings show that indigenous languages have influenced all varieties of Ecuadorian Spanish at all levels of linguistic inquiry. The research presented is noteworthy in its contribution to language contact theories, language and migration studies, and the evolution of Spanish. These studies employ both quantitative and qualitative methodologies and will deepen the reader's understanding of different dialects of Spanish. As the first edited volume on Ecuadorian Spanish, this book brings together cutting-edge research and sets the stage for future work.