The establishment of the B cell repertoire depends on two major parameters. The first is determined by mechanistic processes that give rise to a great diversity of B cell receptors from a combination of multiple gene segments. The second is dominated by selective processes that recruit B cell clones via their immunoglobulln receptors. To assess the impact of these parameters on the composition of B cell repertoire, we constructed a mouse model displaying a B cell repertoire limited in its diversity. To this end, we disrupted the Cχ segment by gene targeting. B cells from such mutant mice do not express the χ light chain. Their light chain repertoire is therefore limited by the expression of only four main λ light chains: λ1, λ2(V2), λ2(Vx) and λ3. In this study we described the proportions of each λ subtype in various lymphold compartments. Our results show that the λ1 subtype is dominant in the spleen and the bone marrow. Moreover, λ1 prevalence is independent of the wild or mutant Cχ genotype. These results suggest that the mechanistic processes are mainly responsible for the bias in λ subtype expression. On the other hand, the λ2(V2) and/or λ3 subtypes are expressed at higher levels in the peritoneal cavity. Their prevalence is again observed regardless of the Cχ genotype and seems to be due to B1 cells. These results suggest that different mechanistic processes could control λ subtype expression in B1 and B2 cell lineages.