355Editorial Scand J Work Environ Health. 2016;42(5):355-358. doi:10.5271/sjweh.3578 Organizational stress management interventions: Is it the singer not the song?Good reasons exist for combating stress at work. It is a burden for individual employees and their families and costly to companies and society. Moreover preventing stress at work is a sign of good corporate citizenship as it respects modern legislation that stimulates the provision of a good quality of working life.In order to recommend good interventions, we need to know which interventions work. Outcome evaluation research is, therefore, important but not enough. We not only need to know "what works", but also "when, how, and why" this may be the case. This means that we need to combine classical effect evaluation research with process evaluation. Combining these two approaches fits in a young scientific discipline: implementation research. Implementation refers to "the way a program is put into practice and delivered to participants" (1). Implementation research crosses traditional disciplinary boundaries, with contributions being made from both occupational and public health domains but also from psychological theories on motivation, behavioral change, and social influence.In a recent commentary, Durlak (1) has highlighted major findings in implementation research. He concludes: "We now know that it is not evidence-based programs that are effective, but it is wellimplemented evidence-based programs that are effective" (p1124). He also explains: "If we do not assess implementation, we do not know if a program has been put to an adequate test. It may fail not because the intervention lacks value, but because the intervention was not implemented at a sufficiently high level to produce its effects" (p1124).Effect-only evaluation data may thus mask intervention effects that are sensitive to variations in intervention processes (2). This all means that checking effects is not enough to determine whether a program works or not. To answer this question properly, we need to open up the black box because we also must know how it was implemented.Ten years earlier -in an occupational health intervention context -Tage Kristensen made comparable arguments (3). Kristensen explained the difference between implementation and theory failure by describing the case of a patient (employee) and a pill (stress intervention): "It does not help that the pill has effect if the patient does not take it, and it does not help that the patient takes the pill if it has no effect" (p207). In both cases, process evaluation is needed to find out what actually happened and make the right decisions to proceed. In the first case (pill not taken), the implementation failed and it is therefore not possible to determine if the program works. The underlying theory still may be right. Had the implementation not been studied, the erroneous conclusion might have been that "the theory was wrong". In this first case, the next step should hence be to work on better implementation. In the se...