This dissertation focuses on processes of analogical extension and morphological syncretism affecting Old and Early Middle English texts written in southern varieties of English. The genitive singular -s inflexion of the a-stems in Old English was preserved and spread to other noun classes in Middle English, which has been well documented in northern dialects (Rodríguez Ledesma 2018 and 2022), but there is no literature to date on similar processes in the southern ones. Similarly, the a-stem nominative and accusative plural -as was extended across Old and Middle English paradigms until, by the end of the period, -es (< OE -as) became the only plural marker left (Lass 1992: 109, Hogg 1992: 138); Rodríguez Ledesma's findings in her analysis of nominative/accusative plural extension (2022a, 2018) show a limited evidence of this process in northern varieties of English. On account of their conservatism, however, West Saxon dialects have not received as much attention by scholars with regard to processes of nominal restructuring. The aim of this dissertation is, therefore, to offer a quantitative study of the processes affecting the declensional system of West Saxon and southern Early Middle English varieties, with a focus on the genitive and nominative/accusative plural cases. It will also aim to determine which variables (date of the texts, type of stem, token frequency) are significant in the spread of these inflections, and which morphological tendencies are involved in the development of both cases. In order to fulfill those objectives, the present work offers a thorough analysis of the genitive singular and nominative/accusative plural inflection of nouns in a variety of texts written in the West Saxon dialect and southern varieties of Early Middle English, considering the variables stem, gender, number, position, function and date. The following Old English texts were provided by the York-Toronto-Helsinki Parsed Corpus of Old English Prose (2003) for the analysis of genitive extension: The Anglo-Saxon Chronicle (Cambridge, Corpus Christi College, 173, 9-10th c.), Alfred’s Introduction to Laws and Laws of Alfred (Cambridge, Corpus Christi College, 173, 9-10th c.), The West Saxon Gospels (Cambridge, Corpus Christi College, 140, early 11th c.), and Adrien and Ritheus (London, British Museum, Cotton Julius A.II, mid-11th c.). For the analysis of Old English nom./acc. plural, The Anglo-Saxon Chronicle and the gospel according to St. Mark from the West Saxon Gospels were selected (from the respective MSS indicated above). The study of analogical extension in Early Middle English is based on the analysis of the corpus material provided by LAEME (Linguistic Atlas of Early Middle English). The manuscripts analyzed are Cambridge, Trinity College B.14.52 (335), entry 4; Cambridge, Corpus Christi College 145; Cambridge, Emmanuel College 27 (I.2.6); London, British Library, Royal 2 F viii; Wells Cathedral Library, Liber Albus I, entry 1 (and entry 2); Aberdeen University Library 154, London, British Library, Additional 46487; and London, British Library, Cotton Roll ii.11, entry 1 (and entry 2). The results of this investigation show that, in a stark contrast to the situation found in Anglian dialects, these analogical transfers are still very incipient in West Saxon, which may be due to the influence of the West Saxon literary language and the corrections made by contemporary scribes following the regularizations adopted by their scriptoria. The increase in the spread of the s-genitive in the singular and the -es (< OE -as) ending in the plural in the Early Middle English period suggests that, in addition to certain limitations that may have been set by the Late West Saxon regulations in scribal communities of practice, these analogical processes vary diatopically, as is always the case, and spread later in the south.