In the past, changes in behavior and in belief have been leading indicators for missionaries that Christian conversion had occurred. But these alone–or even together–are insufficient for a gospel understanding of conversion. For effective biblical mission, Paul G. Hiebert argues, we must add a third element: a change in worldview. Here he offers a comprehensive study of worldview–its philosophy, its history, its characteristics, and the means for understanding it. He then provides a detailed analysis of several worldviews that missionaries must engage today, addressing the impact of each on Christianity and mission. A biblical worldview is outlined for comparison. Finally, Hiebert argues for gospel ministry that seeks to transform people’s worldviews and offers suggestions for how to do so.