Investigation of the relationships between the structure of internal labor markets and the mobility, experience, and income of workers. Industries are classified into three types of structures according to the degree of firm and industry mobility. The central assumption behind the classification scheme is that structure is related to mobility. In particular, relatively low probability of an employee leaving a firm characterizes manorial structure; a relatively high probability of leaving the firm and industry is a measure of unstructured markets; and a large positive difference between the probability of leaving the firm and the probability of leaving the industry is associated with guild structures. The relationships between income and experience across structures are then examined. It is shown that structure manifests itself through variations in the proportions of different types of individuals having pre-established income-experience traits, rather than through the imposition of behavioral patterns on an essentially homogeneous labor force. 26 pp.