This thesis examines the relationship between temporary organising and institutional logics in large-scale project implementation, focusing on two cases: The Irish Rural Electrification Scheme, and Ireland’s National Electronic Health Record Programme. It analyses implementation processes in each case to understand how temporary organising interacts with prevailing institutional logics. Using a multiple case study design and a qualitative methodology, the research explores the complexities and dynamics of temporary organising. Based on insights from the two cases, it develops a novel categorisation of the temporary organising/institutional logic relationship as: Embedded, Constellated, or Decoupled, and identifies four key categories of implementation processes as: Compliance, Competence Building, Collaboration, and Cost (the 4Cs). The findings offer both theoretical contributions, advancing understanding of how temporary organising shapes and is shaped by institutional logics, and practical guidance for managing complex, time-bound projects across instances of temporary organising.