This book is about the hope of the Church in the secular age uninterested in Christianity. In this setting, the theology and practice of missional church is a critical topic. We introduce urban churches in South Korea conducting maeul ministry, Korea’s context-specific practice of the missional church in local communities. The cases are followed by theological reflections to connect the practice with the theology of missional church. These stories of maeul ministry present various examples of church involvement and leadership in social issues of the environment, healthcare, education, and community-building, offering new hope and challenge for the world church. We hope this book will provide new insight and wisdom to church communities and pastors who pursue and practice the missional essence of the church in these changing times.