Technology has been identified as an important strategy in making caring sustainable. This article takes the design process for carer support technology as a lens on the divergent definitions that are in play when governments, technology developers and carers contemplate 'sustainability'. We argue that a central impediment to finding a productive point of overlap among the three perspectives is a predominant focus on carers' needs. We contrast this needs-based approach, and its focus on doing the tasks of care, with a goal-oriented approach focused on being in relationships. Reframing the conversation around goals is important to achieving truly sustainable caring.