The purpose of this portfolio and thesis is to demonstrate the importance of theological reflection upon church planting practice, and by so doing, to resource and equip church planters to think in creative new ways in order to become more effective in missional engagement in forming new communities of faith. This motivation and exploration lies at the heart of each component and individual chapter. The portfolio is comprised of three self contained and coherent pieces of work: a literature review which advocates that theological reflection is a developing concern for church planting, a publishable article that reflects on the nature of the gospel that underpins missional practice, and a research project which aimed to discover how different church planting tribes were engaging in theological reflection, and what issues and lessons were still needing to be learned and further explored. The thesis, building on the work of the portfolio, gives an extended Trinitarian theological reflection upon church planting practice in relation to the themes of creation, context and community. It has attempted to intentionally reflect upon the missional practice of church planting through Trinitarian perspectives, in order that it may be more robust, enriched and rooted in God's own life and story. Trinitarian perspectives on church planting are at best embryonic, and the renewal of interest in the doctrine of the Trinity has stimulated me to write a Trinitarian missiology for church planting that offers fresh theological insights and practical missional applications. Through dialoguing extensively with the Trinitarian creation theology of Jürgen Moltmann, the Trinitarian contextual missiology of Lesslie Newbigin and Timothy Tennent, and the Trinitarian ecclesiologies of Miroslav Volf, Leonardo Boff and Catherine Mowry LaCugna, I believe their collective contributions have much to offer church planting today.