South Africa's Just Energy Transition (JET) from coal to renewable energy in response to climate change mitigation policies comes packaged with social costs that these mitigation policies tend to overlook, considering their focus on carbon emission reduction. The paper argues that Social Impact Assessments (SIAs), a component of Environmental Impact Assessments (EIAs) focused on social impact mitigation, can be a long-term approach to closing the social cost gap. Against this backdrop, the paper's arguments were informed by a literature analysis on SIAs and the Just Energy Transition, semi-structured interviews, and surveys with 230 participants, including experts, from Kriel and Carolina in Mpumalanga, South Africa. The findings point to skills development barriers such as poor school attendance, a lack of alignment between existing curriculum design and labour markets, and students' low aptitude for STEM subjects. It also identifies community sustainability issues linked to poor public participation, gender inequalities in land reform and economic participation, and culturally disruptive displacements that will intensify as the energy shift unfolds. The paper submits that SIAs, if incorporated into mainstream energy transition planning, might be a long-term approach to mitigating societal costs and can support socially responsible policies. [ABSTRACT FROM AUTHOR]