This report is an exploratory application of a dynamic mathematical model to express a theory of changes in youth's career expectations over time. Main content is divided into two focuses: (1) theoretical interpretations of the differential equations which embody the mathematical model and (2) reporting and discussion of the results of preliminary data analyses. Following an introduction (chapter 1), chapter 2 presents several interpretations of the differential equations. It reviews and relates the status-attainment and differential equation models. Chapter 3 describes sampling procedures, methods of data collection, and data coding; gives operational definitions for all variables used in the report; and discusses analytic methods. Chapter 4 contains numerical estimates of the fundamental parameters of the differential-equation model. It presents the specific form of the model used to generate the data and then discusses empirical results for white males and offers race and sex comparisons. Chapter 5 summarizes findings and sets forth conclusions. Appendixes, amounting to over one-half of the report, include questionnaires used during data collection for wave two; detailed explication of instrumentation, data collection procedures, and data coding and correction procedures used during the first and second measurement points of the study; and means, standard deviations, and correlations for variables used in the report. (YLB)