In these studies we have emphasized the apparent developmental hierarchy of B cell development and assigned a role for the multispecific self idiotype reactive B cells which develop first, in promoting the development of later appearing clones of B cells. These early sets of interconnecting clones of B cells bridge between clones of cells involved in such disparate responses as anti-PC and anti-DEX. Interference with these idiotype directed interactions results in deficiencies in the adult B cell repertoire with respect to these responses. These idiotype directed interactions appear to be bidirectional in that interference with either antigen, Ab1, Ab2, Ab3, and Ab4 during neonatal life all produce striking effects on the adult responses to these antigens. These results strongly suggest that early idiotype directed interactions between B cells are essential for the establishment of the adult B cell repertoire.