The frequencies at which four VH gene families pair with the lambda 1 light (L) chain were determined by sequential hybridization of VH- and lambda 1-specific DNA probes to mitogen-induced colonies of B cells. Analysis of pair frequencies indicates that the repertoire of lambda L chain antibodies is generated by the stochastic pairing of smaller 3'-to-mid-locus VH gene families (X-24, S107, Q52). However, the large 5' VH J558 family appeared to associate with the lambda 1 L chain non-stochastically; the frequency of VHJ558/lambda 1+ colonies among all lambda 1+ colonies was significantly lower than the frequency of J558 expression among all (C mu+) B cell colonies. This difference suggests that selection, either intrinsic at the level of rearrangement or heavy and L chain pairing, or extrinsic following surface immunoglobulin expression, may operate to shape the lambda antibody repertoire prior to the introduction of exogenous antigen.