History has shown that despite favourable changes in policy and perception, undesirable or ineffective educational practices in the Caribbean have remained largely unchanged, or superficially or inadequately changed. It has also shown that high stakes summative assessment wields considerable influence on the content to which students are exposed and the teaching and assessment methodologies used in the classroom through the widespread practice of teaching to the test. It is against this background that this paper purports that the integration of sustainable development competences (SDCs) can be advanced through high stakes assessments by capitalizing on the widespread practice of teaching to the test. By focusing specifically on the school-based assessment (SBAs) component of the summative, high stakes examinations used by the Caribbean Examinations Council, the paper examines how SBAs can be optimized to measure and thereby advance the integration of SDCs. The paper opines that through its allowance for formative assessment, integrated assessment, inquiry-based projects and group work, SBAs are optimal for assessing and furthering SDC development.