Public procurement policies requiring frequent tenders and defined contracts give rise to expectations of low cost quality services and present management challenges for the post tender contract. Frequent tendering undermines the principal agent relationship and contract incompleteness allows unforeseen contingencies to threaten the specified outcomes. This thesis examines seven cases of facilities management contracts in three third-level educational institutions. Using a qualitative and interpretative methodology, the study takes an inductive theory building approach to how and why managers address challenges, and develops a conceptual model of ex post management mechanisms through the lenses of agency theory, the psychological contract, and signals. It finds that the principal agent relationship is based on both written and psychological contracts, and mechanisms include incentives, information systems, and psychological contract signals. It also finds that, rather than pursuing the terms of the written contract which are frequently incomplete, the principal and agent work together towards the broader goals of the psychological contract to maintain the contract benefits. While it has the limitations of a theory building and social constructionist approach, it offers theoretic and management relevance. It extends agency theory in public contracts by highlighting the importance of information systems, and the psychological contract in the principal agent relationship by identifying the principal’s influences and the relevance of agent’s perceived obligations in deciding responses. Through understanding these ex post mechanisms, managers may address the inevitable challenges of incomplete contracts, and foster improved responses towards optimal cost and quality outcomes.