Knowledge regarding the effects on employees of occupational intervention programs targeting psychosocial factors at work, including job demands, job resources, and personal resources, is limited and existing studies show mixed findings. This study aimed to investigate potential effects on employees’ job demands (i.e., workload, unnecessary tasks, unreasonable tasks), job resources (i.e., feedback, control, goal clarity), and personal resources (i.e., signaling and limit-setting strategies) of an intervention targeting managers’ ways of improving the psychosocial work environment among their staff (SWEActManager). Questionnaire data from employees (n = 40) of a Swedish municipality, whose managers (n = 4) participated in the program, and referents (n = 58 employees), were collected before and after the program. The program included four three-hour workshops delivered during a six-week period. Results from 2(group) × 2(time) ANOVAs showed that all three demands increased over time, while job control decreased. There were no significant group effects. One interaction effect only was significant: Unnecessary tasks increased more among referents than in the intervention group. The few significant short-term effects probably relate to challenges in designing and implementing organizational interventions targeting managers, and evaluating their effects among subordinates. This study adds to the limited research regarding the effects of organizational psychosocial interventions, including managers for their subordinates’ demands and resources in a changing working life.