ABSTRACT Although trust between social workers and their clients emerges as a critical factor in social work, it has often been taken for granted and rarely placed under detailed scrutiny in social work research. This study explores the elements on which clients’ trust is built, and social workers’ trust-building practices in gerontological social work (GSW) in Finland. We analysed seven focus group discussions of gerontological social workers abductively, using Russell Hardin’s model of trust as an analytical tool. This study identifies six elements of clients’ trust: (1) trust in the individual social worker and in the institution, (2) trust as mutually recognised goals, (3) trust in the professional’s competence, (4) trust as a risk, (5) trust as dynamic, (6) trust as cognitive. A social worker builds trust by listening carefully to clients, considering their interests when choosing their own goals and actions, clearly articulating the goals and premises of social work, and demonstrating that the social worker can contribute meaningfully to the client’s life. In GSW, clients’ distrust and refusal of services are common. Consequently, trust-building often requires plenty of time, creativity and perseverance from the social worker. This is challenged by the fact that there is not always enough time to build trust, trust’s essential nature is not often recognised in the service system, and social workers may lack competence and understanding of the elements of trust and trust-building. In order to meet older adults’ complex needs, it is essential to meet these challenges and place trust at the centre of GSW.