The Life of Catalina de Erauso, the Lieutenant Nun: An Early Modern Autobiography examines Vida y sucesos de la Monja Alférez as a form of autobiography through a comparative study with early-modern secular life narratives: the picaresque novels La vida de Lazarillo de Tormes, y de sus fortunas y adversidades (anonymous), La pícara Justina by Francisco López de Úbeda, the chronicle Relación que dio Alvar Núñez Cabeza de Vaca de lo acaescido en las Indias en la armada donde yva por governador Pánfilo de Narváez desde el año de veynte y siete hasta el año de treinta y seis que bolvió a Sevilla con tres de su compañía by Cabeza de Vaca and the soldier’s narrative Vida, nacimiento, padres, y crianza del Capitán Alonso de Contreras natural de Madrid Cavallero del orden de San Juan Comendador de una de sus encomiendas en Castilla, escrita por el mismo by Alonso de Contreras. Two questions are addressed: How is Vida y sucesos similar to or different from picaresque novels, chronicles of the New World, and soldiers’ narratives? How are the similarities and differences between Vida y sucesos and these forms of writing related to theoretical parameters for an autobiography? In order to conduct this comparative analysis, four theoretical parameters are established for assessing autobiographical texts. These parameters (coincidence of narrator and protagonist, historical referentiality, whether the subjective narration has a plausible basis in the experience and belief structure of the narrator and the intention of the narrator to tell an autobiographical truth) are based upon the critical approach of hybridity and intersubjectivity, but also draw upon related theoretical work. This book argues that Vida y sucesos should be considered as a form of autobiography, with the understanding that autobiography is an intersubjective and hybrid form or a forma fronteriza.