Research indicates that parental involvement in children's education is positively related to academic achievement in mathematics; however, there are few studies on the role of parental involvement in the context of developing countries. The purpose of this paper is to document the iterative development using design-based research (DBR) of a home-based intervention intended to support parents' involvement with their children in mathematics within the Jamaican cultural context. Key components of the homebased intervention included (a) six sets of mathematics-learning materials, each covering foundational early mathematics concepts, and (b) educator-led workshops to support parents' understanding of the mathematics concepts. Four phases of the DBR process were implemented to create a usable and accessible intervention that was culturally relevant. These phases included (a) developing prototype materials using evidence-based practices and considering local contexts; (b) validating the prototype materials with focus groups comprised of multiple stakeholders; (c) evaluating the cultural relevance of the materials through external review; and (d) examining the feasibility of one set of mathematics learning materials through a small-scale study. Though not reported as part of this paper, we hypothesize that parents' involvement with their children will increase with the implementation of the intervention.