This chapter presents a case study of Mater Misericordiae Limited to demonstrate how green human resource management (GHRM) practices can be effectively integrated into organisational practice. It focuses on the work of Renwick, Redman, and Maguire and frame the case using the Ability–Motivation–Opportunity (AMO) theory. The chapter describes the organisation, its history and underlying ethos, and the origins of the organisation's sustainability journey. At the beginning of the organisation's sustainability journey, focus groups and interviews were conducted with staff to gauge their support and identify ways to encourage Environmental Sustainability practices. The chapter examines the key dimensions of the AMO theory and demonstrates how Mater has effectively embedded these dimensions into their day-to-day practice. AMO theory suggests that employee performance is a function of the three essential components of ability, motivation, and opportunity. This theory has become an effective framework to explain how human resource policies can influence performance.