Although expressed emotion (EE) has been demonstrated to be associated with the course of schizophrenia, the nature of this relationship is unclear. This study proposes that testing for curvilinear relationships can identify the specific nature of the relationships between EE indices and relapse. The utility of curvilinear models was explored through a reanalysis of data from a prior study of EE among Mexican-Americans (Karno et al., 1987). The results suggest that the relationship between the EE index of emotional overinvolvement (EOI) and relapse is curvilinear and that high levels of EOI may exert a toxic effect on course of illness whereas medium levels of EOI may be protective. The relationship between the EE index of warmth and relapse is also curvilinear and high levels of warmth appear to exert a protective effect on the course of illness. The role of culture is explored in explaining the specific manner in which EE relates to relapse among Mexican-Americans. Copyright © 2006 John Wiley & Sons, Ltd.