2 longitudinal studies covering a 1-year and a 3-year interval, respectively were conducted on 2 samples of boys aged 13 years (N1=85, N2=201). On the basis of an adaptation of multimethod-multivariable analysis and other analyses it was found that information contained in the 4 rating dimensions under study to an overwhelming degree reflected characteristics of the boys, not rater biases. The results indicated very high or high degrees of stability over time in the dimensions studied concerning aggression and peer acceptance. The results for the aggressive area were construed as strong evidence for assuming relatively stable, individual-differentiating reaction tendencies or motive systems within the boys. The findings also provided strong evidence that certain aspects of each boy's interpersonal environment were stably different for different boys.