According to the "healthy worker" hypothesis, good health selects women into the employment role; conversely, the social causation hypothesis argues that important social roles such as employment can contribute to health. The relationship between these two variables may be of special concern to women at midlife, as both issues become increasingly salient. In this paper a model hypothesizing a nonrecursive (reciprocal) causal relationship between employment (hours employed) and health was presented. Because of the importance of both employment and health for women at midlife, the model was tested in a sample of 463 women ages 40- 64 from a national cross-sectional dataset. Two-stage least squares regression supported the hypothesis that employment and health have a positive reciprocal relationship for women at midlife. In addition, married women and those with a child had better health but were likely to work fewer hours for pay. The same model tested in 21 to 39-year-old women was not significant. The results serve to emphasize the importance of examining assumptions about direction of causality in research on work and well-being at midlife.