Background and Purpose: Various plant-derived compounds can activate immune responses against bacterial infections, and this property contributes to them being developed as effective and safe adjuvants for vaccines. In this study, the potential adjuvant effects of a galactolipid-enriched fraction generated from the medicinal plant Crassocephalum rabens (designated CRA) were evaluated. Experimental Approaches: Heat shock protein 60 of periodontal disease pathogen Actinobacillus actinomycetemcomitans (AaHSP60) was taken as an antigen and mixed with CRA. The AaHSP60/CRA mixture was then injected subcutaneously into the BALB/c mice. Titers and affinity of specific antibodies were measured by ELISA. Cytokine profiles in mouse serum or culture media of AaHSP60/CRA-treated splenocytes were analyzed by cytokine multiplex assay and ELISA kits. B cell differentiation and macrophage activation were determined by phenotyping. Key Results: CRA dramatically enhanced specific antibody titers and induced Ig class switch as shown by increases in the IgG2a, IgG2b and IgG3 proportions of total Ig in mouse serum. Furthermore, CRA-induced anti-AaHSP60 antibodies had cross-reactivity to other bacterial HSP60s. Cell based and animal results showed that CRA triggered IL-21 and B cell activating factor (BAFF) release that led to B cell differentiation. CRA also enhanced cell proliferation, uptake ability, and antigen presentation in mouse phagocytes. Conclusion and Implications: CRA served as a vaccine adjuvant that enhance mouse immunity against pathogenic antigens. CRA strengthened the activation and capabilities of phagocytes and B cells. Therefore, CRA may be a promising adjuvant for bacterial vaccines including periodontal disease.