Knowledge about the wellbeing of medical professionals working through the COVID-19 pandemic and its practice implications is expanding extensively. It remains, however, sparse for 'essential' (aka critical) community practitioners. We addressed this gap using a repeated-measures analysis of COVID-pandemic wellbeing experiences of critical, homeless-sector practitioners. An explanatory sequential mixed-methods design, capitalizing on a pre-pandemic needs-analysis, longitudinally followed 42 practitioners (30 support staff and 12 project managers) in a single, national UK-based homeless-support organization. Practitioners completed measures, prior to and six months into the COVID-pandemic, of: mental wellbeing, secondary traumatic stress (STS), burnout and compassion satisfaction. Our qualitative questions captured practitioners’ wellbeing, working practice and support experiences in COVID-times. While the pandemic detrimentally impacted on levels of STS, burnout, and general wellbeing in support staff, managers’ mental and professional wellbeing remained consistent with their pre-pandemic scores. Our qualitative analysis identified intense stressors in support staff (not shared by project managers) which hampered client-practitioner relationships and encouraged 'them-and-us' support staff-manager dynamics. The identified nuanced (and contrasting) stressors experienced by practitioners in a national UK homeless-support organization offer insight into what residual and new wellbeing challenges need to be addressed in research and practice as we recover and progress from the pandemic.