This article reports a model-fitting analysis of the covariance structure of the field dependence-independence data. A model is used which includes additive and non-additive genetic parameters, and shared and nonshared environmental parameters that permit different estimates for different types of relatives. The opportunity is taken here to explicate the use of LISREL for such purposes. The results indicate that, when assortative mating is included in the model, nonadditive, as well as additive genetic variance is important for the field dependence-independence cognitive style. Broad heritability is estimated to be 0. 50. Another interesting result is that the influence of nonshared environment seems to be crucial when accounting for variance in different groups of relatives.