This presentation discusses linguistic phenomena in Santomense Portuguese and Principense Portuguese (PST and PP) and its historical background. The emergence of these varieties in São Tomé and Príncipe (STP) occurred at the end of the colonial rule by Portugal in a plurilingual environment, where an initial development as a second language led to the establishment of Portuguese as a mother tongue (in the last 60 years). Thus, based on data collected during fieldwork in STP, we present a synchronic panorama of a variety of phenomena such as: vowel harmony, segmental deletion, rhotic contrast loss, mid-vowel neutralization, gender agreement, and toponymy. The examination of these processes allows us to conclude that the development of local varieties in STP is evident, constituting the country’s macro variety (PSTP).