H. Theil has made important contributions to the analysis of simultaneous-equations models. This paper gives an exposition of some closely related recent developments in microeconometrics, with a focus on efforts to develop robust methods for dynamic policy evaluation. We set the stage with a brief discussion of the static treatment-effect approach to program evaluation and non-parametric structural models. We then critically analyze the dynamic treatment-effects approach adopted from statistics. Finally, we review the eventhistory approach. We clarify some of the fundamental problems that arise in the analysis of such models by rephrasing a canonical version as a simultaneous-equations model.