INTRODUCTION Since the publication 10 years ago of my previous survey of the literature on internal migration, a number of important advances have occurred in migration research.' Although the prior survey serves as a point of departure for this paper, earlier contributions are not completely ignored. Space limitations prevent a detailed discussion of many important advances concerning internal migration in less developed countries, as well as those dealing with international migration.2 During the last 15 years fundamental changes have occurred in US. internal migration patterns. These changes have been recognized for approximately the last 10 years and have given rise to an important, until now primarily descriptive, body of literature that warrants attention. In general, migration research has maintained its strong orientation toward the determinants as opposed to the consequences of migration, and consequently most of the recent advances have concerned the causes of migration. During this period several noteworthy theoretical contributions have been made involving both new independent and new dependent variables. New modeling perspectives have been adopted, and alternative functional forms of migration equations have been considered. Moreover, a number of significant new empirical insights have developed. Certain of these findings have been closely related to theoretical innovations, but many awaited the development of new data sets. Two types of data particularly stand out-microdata relating to migration and migration time series. These types of data have also allowed the application of several refinements in econometric methodology to migration research.The paper begins with a discussion of the changes that have occurred during the recent past in U.S. internal migration patterns. These changes have provided a stimulus to a certain line of research. In addition to this discussion, Section 2 presents an assessment of the state of knowledge concerning these phenomena. Section 3 provides a more abstract discussion of the determinants of migration, including a treatment of both recent theoretical and empirical literature. The