{"p"=>"This study provides a comparative analysis of the thematic evolution of research in Waste Management (WM), Circular Economy (CE), and their joint research domain (WM&CE) over the period 2004–2024. Using bibliometric techniques —specifically co-word analysis and strategic mapping— the study examines the evolution of scientific production and conceptual structures across these domains. Based on a representative sample of articles indexed in Web of Science and Scopus, the research pursues two objectives: (1) to examine the evolution of scientific output through key bibliometric indicators such as publication volume, authorship, citations, and international collaboration; and (2) to compare the diachronic thematic trajectories of WM, CE, and WM&CE. The results reveal differentiated modes of knowledge development. WM follows a stable and mature trajectory characterised by strong thematic continuity, but also by signs of conceptual lock-in that constrain the consolidation of novel approaches. CE exhibits rapid growth and dense international collaboration networks, yet many emerging themes show limited stability and fail to progress towards mainstream positions. The WM&CE domain occupies an intermediate position: while more recent and smaller in scale, it displays a coherent set of promising and motor themes combined with low stability values that reflect processes of conceptual recomposition. From a theoretical perspective, the findings suggest that thematic evolution does not always follow a linear niche-to-mainstream progression. Instead, themes often persist through reinterpretation and expansion, leading to non-linear movements across strategic positions. The study contributes methodologically by applying a longitudinal bibliometric approach, empirically by offering a systematic comparison of three key sustainability-related domains, and theoretically by advancing the understanding of knowledge accumulation and research lock-in."}