Abstract The comparative strengths of Agile and traditional plan-driven software development methodologies are among the most extensively documented topics in software engineering research, and a narrow restatement of that comparison offers little new to the literature. This paper instead synthesises the comparative evidence with a specific focus on a gap that recurs across the literature but is rarely addressed directly: how organisational governance structures should be adapted, rather than simply bypassed or left unreconciled, when Agile methods are adopted at scale. Drawing on quantitative project-outcome evidence (the Standish Group CHAOS Reports, Serrador and Pinto’s empirical analysis), industry adoption surveys (State of Agile, PMI Pulse of the Profession), and the large-scale Agile transformation literature (Dikert et al., Rigby et al., Moe et al.), we show that the documented failure modes of large-scale Agile adoption — cultural resistance, fragmented governance, and distributed-team coordination breakdown — are predominantly governance failures rather than methodological failures of Agile itself. We synthesise the limited existing evidence on hybrid Agile–structured approaches and argue that the relevant research question is no longer “Agile or traditional” but how governance frameworks should be redesigned to support Agile delivery without forfeiting the accountability traditional methods provide, particularly in regulated and safety-critical contexts. Keywords Agile software development, Waterfall, software engineering methodology, IT governance, large-scale Agile transformation, hybrid project management.