Interpersonal work resources and school personnel well-being before and after lockdown during the first phase of the COVID-19 pandemic in Finland

•The two-month school lockdown in spring 2020 was associated with increased - exhaustion, but not with increased cynicism among school personnel.•Work engagement and a sense of belonging decreased, on average, but not for all school personnel.•The availability of collegial relationships prior to and during lockdown was an important resource for maintaining work engagement and a sense of belonging.•Experiences of leadership support during lockdown varied as sources of job resources. This two-wave mixed-methods study used the job demands and resources model to examine the effects of the COVID-19 pandemic on school personnel's work well-being (including burnout, work engagement, and sense of belonging) in spring 2020 in Finland in particular with respect to collegial relationships (respectful engagement) and leadership support. A pre-lockdown survey was administered prior to the pandemic (in January–February, n = 437) and a post-lockdown survey was administered after the two-month lockdown (at the end of May, n = 270). At post-lockdown, the school personnel reported, on average, more exhaustion, less work engagement (measured as enthusiasm and energy at work), and a decreased sense of belonging than before lockdown. The period of lockdown was characterized as highly burdening, and many had missed their work communities. On the other hand, work absorption related to work engagement showed an increase, and there was no change in burnout with respect to cynicism; only a few expressed high levels of cynicism, whereas many reported positive experiences. The effects of pre-lockdown interpersonal relationships on school personnel's well-being during lockdown were mediated by pre-lockdown well-being. Respectful engagement was also directly associated with a higher sense of belonging during lockdown over and above the pre-lockdown sense of belonging. Collegial relationships were described as salient and available work resources during lockdown, whereas leadership was often perceived negatively during pandemics. The findings underline the importance of fostering respectful work community interactions and improving supportive school leadership to cope with crises while maintaining high-quality teaching and student support.