The evolution of Spanish past forms The Evolution of Spanish Past Forms examines how Spanish past forms have changed diachronically. With examples from Medieval Spanish Golden Age Spanish and Modern Spanish literary works this book demonstrates how language is dynamic and susceptible to change. The past forms considered here include the preterit the imperfect the imperfect progressive with estar (temporal to be) the present perfect the imperfect progressive with other auxiliary verbs the preterit progressive with estar and the preterit progressive with other auxiliary verbs. This book will be of interest to scholars and graduate students investigating tense and aspect phenomena in Spanish and other languages grammaticalization processes and language variation and change Grammaticalization theory Previous studies on Spanish past forms The study Results Discussion and conclusions.