Substance use disorder constituted a global social challenge, shaping individuals’ health, social relationships, and living conditions, homelessness, mental ill health, and social marginalisation. Within social work, housing based services provide support for people experiencing substance use problems. The aim of this study is to explore how professional treatment staff within low threshold and supported accommodation services experience their work with people facing substance use problems. How staff describe their interventions, working methods, and approaches to client interaction, and how these may shape clients’ circumstances and possibilities for change. The study is guided by two research questions: (1) which factors do staff describe as significant in contributing to an increase or decrease in clients’ substance use problems, and (2) how do staff perceive that their approach and ways of working influence clients’ change processes? A qualitative study was conducted using semi structured interviews. The study’s findings identify three central and recurring themes. The first concerns social relationships and networks, which participants describe as functioning as both risk and protective factors. Substance use is portrayed as connected to forms of belonging within drug using environments, where relationships and shared community may contribute to the maintenance of use. The second theme highlights individuals’ life circumstances, with everyday routines and practical stability described as foundational. The third theme addresses staff approaches and relational work, described as crucial for building trust and enabling sustained change efforts. The study suggests that change processes among people experiencing substance use problems presuppose the stabilisation of life circumstances, access to secure and sustainable relationships, and a relational, trust promoting approach as an integrated element of change work. A favourable change trajectory thus appears contingent upon both social conditions and access to relevant resources and interventions within social work practice.