The report identifies and describes the effects of the major determinants of participation in the experimental program and provides a multivariate description of the participants. Section II provides background information on the spread of program knowledge and growth of program operations from the start-up phase to a state of equilibrium. Section III summarizes the detailed analyses of the steps to participation reported by Wendt (1981) and Coleman (1981). Section IV integrates these analyses into a single model of the probability that an eligible household will ever receive payments. Section V discusses delays to enrollment to explain how the cost-benefit framework can accommodate the random events that both cause transitions into and out of eligibility and determine dates of enrollment. Section VI analyzes the outcome of the participation process by answering two questions. (1) Were needier households more or less likely to be served? (2) Did indentifiable groups of households participate less than others at the same level of need?