An ex post facto study, initiated at the request of the National Institute for Working Life (NIWL) in Umeå, aimed at evaluating the impact of an educational/social program, targeted towards working life and dealing with work environment issues, such as noise, vibration and non-ionised radiation is described. The pedagogical principle on which the program is based is a strategic use of a, so called, "ripple effect", that is, where participants in the educational program are specifically expected to convey their knowledge gained on to other colleagues in the workplace. This "ripple effect" is ultimately supposed to result in an improvement of workplace safety behavior. The program has been in operation since 1997. Ex post facto data will be gathered at selected workplaces from the ultimate targets of the "ripple effect". Difficulties and problems associated with ex post facto evaluations; of evaluating "ripple effects"; and of deciding on strategy and methodology for ex post facto "ripple effect"-evaluations will be explored.