There has been some suggestion that the author was originally of Jewish extraction, but in 1492 had had to convert to Catholicism to avoid being expelled from Spain; that might explain the animosity towards the Catholic Church displayed in the book.{{citation needed|date=June 2013}} Apart from the chronological difficulties this hypothesis presents, Catholic criticism of Catholic clergy, including the Pope, had had a long and even reputable tradition that can be seen in the works of famous Catholic writers such as [[Geoffrey Chaucer|Chaucer]], [[Dante Alighieri|Dante]] or [[Erasmus]].
Documents recentlybrought discoveredto light by the Spanish [[Palaeography|palaeographer]] [[Mercedes Agulló]] in 2010 support the hypothesis that the author was, in fact, Diego Hurtado de Mendoza.<ref>{{cite web |url=httphttps://www.elculturalelespanol.escom/version_papelel-cultural/LETRASletras/2674220100305/El_Lazarillo_no_es_anonimolazarillo-no-anonimo/21498387_0.html |publisher=El MundoEspañol |title=El Lazarillo no es anónimo (Spanish)|access-date=11 March 2010|language=es}}</ref> In 2023, researchers Mariano Calvo and José María Martínez have proposed and documented that the most likely author of "El Lazarillo" might be [[Juan de Valdés]]. They found their hypothesis on biographical, historical and linguistic recurrences between "El Lazarillo" and Valdes' works.<ref>{{cite news |last1=Martínez Domingo |first1=José María |title=Sobre el autor de El Lazarillo o, de nuevo, sobre Juan de Valdés |url=https://www.janusdigital.es/articulo.htm?id=254 |work=Janus |date=13 September 2023 |language=es}}</ref>
Most recently, researchers Mariano Calvo and José María Martínez have proposed and documented that the most likely author of "El Lazarillo" seems to be Juan de Valdés. They found their hypothesis on biographical, historical and linguistic recurrences between "El Lazarillo" and Valdes' works. Their hypothesis are summarized in Martínez' article titled "Sobre el autor de 'El Lazarillo' o, de nuevo, sobre Juan de Valdés", and published recently in "Janus", an academic journal specialized in Golden Age Spanish Literature.[https://www.janusdigital.es/articulo.htm?id=254]
