Democracies are extremely unlikely to wage war against other democracies - this main proposition of the Democratic Peace theory constitutes the starting point for this volume. Chapters authored by experts from different parts of the world explore the concept of Democratic Peace in greater depth in relation to selected issue areas and in comparison to other concepts such as security communities or concerts of powers. The role and significance of international organizations and gender equality, for instance, are discussed and assessed in this context. The objective guiding this exercise is to give an answer to the question as to whether Democratic Peace and the other two concepts - i.e. security communities and concerts of powers - can provide a solution to today's security challenges and constitute a guide to peaceful co-existence and conflict settlement. So, the chapters discuss intellectual frameworks at some length, at the same time, reflecting on potential inferences for the outside world and highlighting associated challenges, limits, or even possible adverse implications.