[eng] Most adjectives in English have two options to express the comparative form: synthetically (e.g., cleverer) or analytically (e.g., more clever). The coexistence and availability of both comparative forms may generate confusion on which one to use, and which factors determine the choice of either form. While traditional grammars attributed length (measured in number of syllables) as the main determinant for comparative variation (Sweet 1891, Quirk et al., 1985, Biber et al., 1999, Huddleston and Pullum 2002), recent studies show that the situation is more complex and list a set of determinants that influence this alternation. Despite of this, a scarce amount of research has actually focused on the coexistence of comparative forms in varieties of English other than the standard American and British English. Hence, the present paper analyses the main factors that underlie comparative alternation through an in-depth focus on the occurrences of inflectional and periphrastic forms of a selection of adjectives in the following language varieties: South African, Nigerian, Ghanaian, Kenyan, and Tanzanian Englishes. In line with contemporary studies, results show that comparative alternation is predominantly governed by phonological factors while other frequently mentioned factors such as ‘colonial lag’ are not so determining.