‘Work ability’ is a multidimensional concept with importance for both society and the individual. The overall aim of this thesis was to illuminate work ability from the perspective of individuals (Studies I, III), rehabilitation (Study II) and employers (Study IV). In Study I five focus-group interviews were conducted with a total of 16 former unemployed sickness absentee participants. The interviews focused on their experiences of the environmental impact on return to work. The participants expressed a changed self-image and life rhythm. A need for reorientation and support from professionals was stressed. Experiences of being stuck in a ‘time quarantine’, i.e. a long and destructive wait for support, were also revealed. Study II was a randomised controlled study evaluating the interventional capacity of problem-based method (PBM) groups regarding anxiety, depression and stress and work ability compared to cognitive behavioural therapy (CBT) as a method within the Rehabilitation Guarantee. Effects were measured with psychometric instruments. The participants, 22 in the PBM group and 28 in the CBT group, were persons on sick leave because of common mental disorders. Within-group analysis showed significant lower degree of symptoms regarding anxiety and depression for both interventions. Between-group analysis showed significant lower degree of symptoms for CBT regarding anxiety, depression and stress. Within-group analysis of work ability showed significant improvement in one (out of five) subscales for the PBM group and in four for the CBT group. No significant between-group differences were found regarding work ability. In Study III, 16 participants were interviewed after completed interventions in Study II, eight from each intervention group. The interviews focused on their experiences from the interventions and the impact on their ability to work and perform other everyday activities. The interventions were experienced as having a positive impact on their ability to work and perform other everyday activities in a more sustainable way. Reflecting on behaviour and achieving limiting strategies were perceived as helpful in both interventions, although varying abilities to incorporate strategies were described. The findings support the use of active coping-developing interventions rather than passive treatments. Study IV included interviews with 12 employers and investigated their conceptions of ‘work ability’. In the results three domains were identified: ‘employees’ contributions to work ability’, ‘employers’ contributions to work ability’ and ‘circumstances with limited work ability’. Work ability was regarded as a tool in production and its output, production, was the main issue. The employees’ commitment could bridge other shortcomings. In summary, in the work rehabilitation process, different perspectives on work ability need to be considered in order to improve not only individual performance but also rehabilitation interventions, work-places and everyday circumstances. Clearly pronounced perspectives can contribute to better illustrating the dynamic within the relational and multifaceted concept of ‘work ability’. The ability to work can thus be enhanced through improving individual abilities, discovered through reorientation and created through support and adaptation.