This research is guided by the assertion that, as American society journeys through the post-modern transition, many established churches are struggling to respond adequately to cultural change within a fragmented generational context. It further is argued that the resulting ineffectiveness of many of these churches in transmitting the Christian tradition to Gen Xers, the first post-modern generation, threatens the ability of these churches to sustain their witness through this period. This project advances the hypothesis that, if established churches are to sustain their witness through the post-modern transition, they must engage in a process of missional renewal that encompasses Generation X. When considered from both a sociological and a theological perspective, this process must be seen as entailing a commitment to intergenerational reconciliation and justice. Chapter one provides an introduction to this study and explains how it is situated within the discipline of Practical Theology. Following Heitink (1999:6), Practical Theology is defined as “the mediation of the Christian faith in the praxis of modern society.” Chapter two offers additional theoretical foundations through an exploration of the intergenerational praxis of the church within the intergenerational praxis of society. In chapter three, essential historical background is provided through an exploration of the influence of modernity in shaping the praxis of American society, as well as the influence of the Christendom paradigm in guiding the church’s praxis. This chapter also explores the emergence of institutional structures that have fostered distance between the generations, as well as the impact of these changes upon the intergenerational praxis of the church. Chapter four examines the complexities associated with the post-modern paradigm shift. Generation X is introduced as a generation whose formative years most closely approximate this period. Generation X is shown to be a misunderstood and maligned generation possessing discontinuous cultural values. In chapter five, the “marriage” of Christendom and modernity is shown to limit the ability of established churches to respond faithfully to the post-modern turn. The intergenerational dynamics of these churches also are shown to hinder their response. This chapter demonstrates that the resulting absence of the first post-modern generation from these churches places their continued viability at risk. Chapter six explores the need for these churches to experience missional renewal. A case is made for the participation of Generation X as a crucial consideration in this pursuit. The issue of “process” is shown to be important in helping churches negotiate the challenges of missional renewal. Chapter seven advances the assertion that, from both theological and sociological perspectives, intergenerational reconciliation and justice must be seen as integral dimensions of the missional renewal process. In chapter eight, the argument developed in the preceding chapters is subjected to empirical evaluation. The results of a survey conducted among churches from five denominations lend credibility to this study’s hypothesis. The final chapter (nine) introduces the “Missional Change Model” as one strategic framework through which established churches might be guided in pursuing missional renewal. This chapter also demonstrates how this model might help to facilitate intergenerational reconciliation and justice.