Abstract
The exchange of linguistic materials between languages which come into contact is indeed reciprocal. The previous accounts of the outcome of contact between Datooga and Sukuma was skewed towards impact of Datooga on Sukuma. Based on ethnolinguistic vitality approach, the Datooga tend to reveal solidarity-related social identity by acquiring their language as a mother tongue. They also reveal prestige-related social identity by acquiring Sukuma language which is the prestigious lingua franca of the Itumba area in Igunga District. Moreover, the Datooga envisaged mechanisms to either isolate out-group members using their ethnonyms. Based on a list of 250 loanwords, this paper highlights the substitutive borrowing of kinship terms and additive borrowing of agricultural terms. The Sukuma loanwords penetrate into the Datooga lexicon.