This paper traces the rising and falling significance of twenty-two topics in digital architectural research. These topics, which are divided into seven primary themes, are examined using a longitudinal analysis (1995 to 2017) of research in the CumInCAD database. This database, which indexes more than 12,000 publications spanning the last four decades, is the largest dedicated resource for digital architectural research. The primary themes examined in this paper include research into: documentation and representation; environmental immersion; transformative methods or approaches; industry applications and impacts; pedagogy and interaction; and cross-disciplinary and sub-disciplinary focus. Some of the specific topics examined within these themes include research trends in BIM, virtual reality, parametric design, rapid-prototyping, the design studio and space syntax. In addition to these primary themes and topics, the longitudinal analysis is also used to examine a further twenty social, cultural and philosophical topics. Some of these secondary themes include crime, homelessness, politics, poverty, gender, emotions, ethics and violence. From this two-part analysis of the prevalence (or lack thereof) of various themes in the last twenty-one years of digital architectural research, the paper identified several challenges for the future. These challenges include the dangers of self-referentiality and insularity, the possible loss of grounding in industrial or professional needs and applications, and the lack of consideration of a growing number of problems facing the modern world.