This thesis is concerned with the relationship between (a) patterns of sociolinguistic variation and (b) issues in theoretical linguistics. The patterns of sociolinguistic variation are derived from data collected from twenty speakers of Tyneside English. The recordings of the speakers were made broadly following a social network model, divided to sample the speech community along parameters of age and gender. The issues in theoretical linguistics concern the semantics and (morpho)syntax of modal verbs in English, and the phonological behaviour of the oral stops in specific linguistic environments. The thesis aims to show how a holistic approach to variation in the speech community, informed by knowledge of both sociolinguistic and formal linguistic theory, can best account for the data. The introduction expands on the aims of this thesis, and provides a more detailed synopsis of the materials in each chapter than is given in this abstract. Chapter 1 briefly summarises certain aspects of the historical evolution of the Tyneside English (TE) accent, along with some analysis of TE syntactic and morphological patterns, to set the main discussion of the variables in the following chapters within a wider context. Chapter 2 provides a discussion of the semantics and (morpho) syntax of the modal verbs in standard English, with some commentary on relevant aspects of the historical evolution of the modals, which draws on theoretical aspects of both the Principles-and-Parameters and Minimalist frameworks. Chapter 3 examines patterns of glottalisation and glottaling in English, with specific reference to previous studies of TE, as well as to relevant work in current phonological theory, particularly Lexical and Metrical Phonology, along with a selective investigation into the historical evolution of these phenomena in TE (using material from the Survey of English Dialects) and other varieties of British English. Chapter 4 considers the issue of gender-based variation and its implications for linguistic maintenance and change. Chapter 5 presents a detailed discussion of the methodology used for the collection of data for this thesis, as well as an analysis of the data itself, and how these data correlate with the various social groups.