Participants' self-reports and measures of attitudes regarding flightdeck management indicate that crew resource management training is favorably received and causes highly significant, positive changes in attitudes regarding crew coordination and personal capabilities. However, a subset of participants reacted negatively to the training and showed boomerangs (negative change) in attitudes. Explorations into the causes of this effect pinpoint personality factors and group dynamics as critical determinants of reactions to training and of the magnitude and direction of attitude change. Implications of these findings for organizations desiring to enhance crew effectiveness are discussed, and areas of needed additional research are described.