This study is a quantitative investigation of a large corpus of 16th-century Slovak administrative-legal texts that analyzes the degree of morphological normalization in early vernacular writing in the Slovak lands (prior to the codification of standard Slovak in the 18th and 19th centuries). Nine key morphological features are examined, and the patterns of normalization observed are assessed to determine their geographical scope and possible linguistic basis. Accompanying the morphological investigation is a theoretical and methodological discussion and application of Diglossia as a sociolinguistic framework for interpretation of the interaction of written Czech and Slovak in precodification Slovakia. This book thus provides both new empirical data on the language of 16th-century Slovak texts, as well as a conceptual model for sociolinguistic interpretation of the early developmental stages of vernacular writing in Slovakia.