This research involves the development of statistical methods for studying the impact of interventions on the social structure of small closed groups. The methods will be used to analyze the impact of an experimental manipulation on the social positions of mainstreamed educable mentally retarded children. The first year's activities laid the theoretical groundwork of a basic method for analyzing the data on single relationship social networks. In this work a method for estimating the parameters of models based on exponential families of distrbutions was produced, numerical algorithms for use in estimation were designed and incorporated into computer programs and routines for producing random matrices from specified models were developed for use in simulation studies. Plans for the second year include continuation of the theoretical work so that models incorporating structural partitions among group members may be estimated. Extensive simulation studies are planned in order to acquire information on the appropriate reference distributions for testing parameter estimates. Empirical studies of the intervention data will commence following successful completion of the simulations. Through these analyses we will attempt to understand the effect that interventions have on the social status of selected individuals and on the overall social structure of the group.