A recent issue of importance in the vast literature on well-being and age concerns the factorial invariance of the construct across age groups. Current wisdom suggests that while differences in loadings exist among age groups, the construction of summary measures introduces little bias. To investigate age and ethnic variation in the meaning of morale, data on Blacks (N=413), Anglos (N=407) and Mexican Americans (N=449) were obtained from interviews which had been conducted with a larger sample of people living in Los Angeles County. Measures of three widely investigated causes of morale (self-assessed health, sex, and income) were included on the survey instrument. Evaluations of three latent structure causal models of morale were conducted. Each model was estimated separately for Blacks, Angelos and Mexican Americans and for those aged 45-54, 55-64 and 65-74 within each of those categories. Analyses of results revealed factorial variance in the meaning of well-being across ethnic groups. In addition to factor structure, differences were uncovered for the causal significance of health and sex. Self-assessed health became less important with advancing age, and sex had markedly different effects for different age groups. The findings indicate that cross-ethnic comparisons of well-being which assume factorial invariance are conceptually flawed. (WAS)