Objective: In this article, we estimate the effect of a multidisciplinary collaboration program on the length of sickness absence. The intention with the program was to avoid long-term sickness absence by providing an early and holistic evaluation of the sick-listed individuals' conditions. The target group was individuals who were at risk of becoming long-term sick. The eligibility criteria were mainly based on register information that we have access to. Methods: Using this register information, we estimate different Cox regression models and apply a nonparametric matching estimator. We have also conducted a small randomized experiment. Results: The result from the randomized experiment is not statistically significant, but the point estimate provides the same result as was found in the observational study: The program prolongs rather than shortens the sickness absence spell. That is, the average sickness absence spell is prolonged by about 3 months. Conclusions: Our main explanation for this discouraging result is that the team focuses too much on rehabilitation rather than encouraging the sick-listed individual to return to work. (Contains 1 figure, 6 tables, and 18 notes.)