This study outlines the development of Portuguese and Spanish verbal morphology from Latin in the context of the Hispanic branch of Romance, with a focus on the conjugational classes, whose number has been reduced to only three in this branch of Western Romance. It is innovative in approaching the topic as a study of sequential productive grammars in an Item and Process type framework. We have found evidence to indicate that in addition to regular phonological change, morphological restructuring and language contact each played an important role in the reclassification of the Latin verb classes II-IV into the verb classes of the Hispano-Romance daughter languages. The historical data studied have been collected from published secondary sources of manuscript and dialectological data and supplemented with data from searchable electronic corpora. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]