Recent trends in syntax and morphology have shown the great importance of doing research on variation in closely related languages. This book centers on the study of the morphology and syntax of the two major Romance Languages spoken in Latin America from this perspective. The works presented here either compare Brazilian Portuguese with European Portuguese or compare Latin American Spanish and Peninsular Spanish, or simply compare Portuguese and its varieties with Spanish and its varieties. The chapters advance on a great variety of theoretical questions related to coordination, clitics, hyper-raising, infinitives, null objects, null subjects, hyper-raising, passives, quantifiers, pseudo-clefts, questions and distributed morphology. Finally, this book provides new empirical findings and enriches the descriptions made about Portuguese and Spanish Spoken in the Americas by providing new generalizations, new data and new statistical evidence that help better understand the nature of such variation. The studies contained in this book show a vast array of new phenomena in these young varieties, offering empirical and theoretical windows to language variation and change.