Rheumatoid arthritis (RA) is a chronic, systemic immune-mediated inflammatory disorder that mainly targets the joints. Several lines of evidence have pointed to B cell function as a critical factor in the development of RA. B cells play several roles in the pathogenesis of RA, such as autoantibody production, antigen presentation and T cell activation, cytokine release, and ectopic lymphoid organogenesis. The success of B cell depletion therapy in RA further supports the relevance of these cells in RA progression. In addition, recent studies have also highlighted the B cell role in the first weeks of RA onset. The present article is a review focused in the immunopathogenic B cell-dependent mechanisms associated with RA development and chronicity and the importance of the recent discoveries documented in untreated very early RA patients with less than 6 weeks of disease duration.