Artificial illumination has had profound and far-reaching impacts on the development, use, and perceptions of urban nights, and has brought with it many benefits. However, in recent years its adverse costs and effects – commonly referred to as light pollution – have emerged as a topic of concern. Nighttime lighting uses enormous amounts of energy, costs billions of dollars annually, can be detrimental to the health of humans and ecosystems, and cuts off access to a starry night sky. Addressing these impacts, and more fundamentally understanding the underlying values shaping contemporary discourse, is a complex and pressing challenge with moral, aesthetic, political, and technical dimensions. This dissertation takes up this challenge by offering a critical examination of the historical roots and normative presuppositions shaping the concept of light pollution. This critique leads to the proposal of an alternative normative framework: instead of focusing on reducing lighting, it argues for fostering darkness in urban nightscapes. A designing for darkness approach is developed on two interrelated levels. The first is conceptual, exploring the relationship between darkness, illumination, and environmental values. The second is practical, proposing first steps towards realizing darker nights via the responsible design of new and emerging technologies, namely LEDs and autonomous vehicles. Taken together, the chapters of this dissertation weave together a critical investigation and constructive contribution to a pressing urban challenge for the 21st century.