This paper reports on part of a longitudinal study of personality and cognitive development in young children, specifically, efforts to identify and measure the concepts of ego control and ego resiliency. The concept of ego control refers to the disposition or threshold of an individual with regard to the expression or containment of impulses and desires. The concept of ego resiliency refers to the capacity of an individual to modify his modal ego control capacity, in either direction, as a function of the demand characteristics of the environmental context. At ages 3.5 and 4.5, for 120 children, ego control and ego resiliency were objectified or indexed in two fundamentally different ways, via a composite score based upon the child's performance in a half dozen independent experimental situations and via a composite score based on the independent Q-sort personality descriptions of each child, offered by their nursery school teachers. In addition, Q-sort descriptions of each child at age 7 were obtained later from their elementary school teachers. (These data are still being analyzed.) The two very different methods used to objectify the concepts of ego control and ego resiliency at three time periods were evaluated with regard to their conceptual and psychometric properties. Results indicate the presence in behavior, for both sexes, over time, and across methods of experimentation and observation, of two context-responsive personality subsystems that separately and in conjunction appear to have consequentiality. (SB)