Although the relationship between unemployment and poor mental well-being has long been an area of interest within behavioural science, the role of state intervention in the unemployment situation has not been thoroughly investigated. This article investigates how unemployment benefit systems and active labour market policy measures affect mental well-being among the unemployed in Sweden. The study uses a longitudinal and nationally representative survey of 3,500 unemployed Swedes. Three different types of active labour market policy measures involving the unemployed were studied, ‘activation’, ‘vocational training’ and ‘work-place participation’ measures. Of these only involvement in ‘workplace participation’ was found to have a clearly positive effect on mental well-being among those participating. Of the two Swedish unemployment benefit systems, the more generous income replacement Unemployment Benefits and the less generous flat rate Cash Unemployment Benefits, only access to income replacement Unemployment Benefits was found to mediate the mental well-being impact of unemployment. The positive effect of access to income replacement Unemployment Benefits was further accentuated when unemployment was prolonged. Those with access to this benefit system seemed to suffer no further deterioration of mental well-being, while the mental well-being of the rest of the unemployed further deteriorated.