Recent developments of higher teacher education in Tanzania have witnessed high student enrolments necessitating change of an emphasis from individual assessment to group-based assessment practices. In this context, informed by the constructivist philosophical perspective, this article reports on the pre-service teachers' voices regarding the prevalence, impacts and counteractive strategies of social loafing. The pre-service teachers are drawn from one higher education institution in Tanzania that serves as a case study. It draws on qualitative data collected from a sample of purposively selected undergraduate pre-service teachers. The study found social loafing tendencies to be commonplace and with far-reaching consequences amongst students as they engaged in group-based assessment tasks, hence calling for measures to redress them. Addressing social loafing in higher teacher education is crucial to avoid compromising the quality of assessment practices in the contexts of ever-rising student enrolments in many lower income countries.