Background
Homeless shelters play a critical role in addressing homelessness and substance use, which is notably high among active shelter users. Individuals residing in homeless shelters often face complex challenges, including addiction, trauma, and social exclusion, making their interaction with staff crucial.

Objectives
This study explores the perspectives of homeless shelter users in three cities with vastly different economies, Manchester UK, Athens Greece and Santiago Chile. By comparing cities globally, we highlight structural and contextual factors shaping shelter effectiveness and approaches, and identify areas for improvement, specifically exploring how shelter environments influence substance use.

Methods
This is a 2024 mixed method comparative study. The dataset includes 68 interviews and 292 questionnaires with service users across 41 organisations in the three sites. Qualitative data were analysed using NVivo 12Plus with an inductive coding approach to identify key things, while quantitative data were analysed with IBM SPSS using descriptive and inferential statistics.

Results
Participants reported that supportive staff behaviour was vital in fostering safety, trust and motivation. Conversely, negative behaviours, linked to staff burnout and lack of training, increased stress and anxiety levels, leading to heightened substance use among residents as a coping mechanism. Participants highlighted the importance of trauma-informed care and consistent support from staff.

Implications
Findings underscore the need for drug policies that address both resident and staff needs within homeless shelters. Policies should include comprehensive training programmes to reduce stigma, enhance cultural competence, improve staff resilience and working conditions, to foster supportive environments that promote well-being and social reintegration.