While the global population continues to rise, many regions are experiencing population decline due to low fertility, outmigration or, most often, a combination of the two trends – and many more are forecast to do so in the future. Economic and demographic theories have so far been unable to offer an unambiguous prediction regarding the consequences of population decline. The 2023 volume of the Vienna Yearbook, “The causes and consequences of depopulation”, provides a wide variety of perspectives on population decline, illustrating that it is a highly multifaceted issue, and that there are no simple theoretical or empirical applications for understanding its causes and consequences, or the potential responses to it. The Debate contributions provide a broader view of and reflections on population decline, while also highlighting the benefits and opportunities associated with it, and ways to manage population changes globally. In contrast, the research articles tend to focus on the challenges of shrinking population that are experienced at a local level. This Introduction gives an overview of the contributions in this volume and the different perspectives they offer.