Immunogenic compositions that elicit immune responses against Norovirus and Sapovirus antigens are described. In particular, the invention relates to polynucleotides encoding one or more capsid proteins or other immunogenic viral polypeptides from one or more strains of Norovirus and/or Sapovirus, coexpression of such immunogenic viral polypeptides with adjuvants, and methods of using the polynucleotides in applications including immunization and production of immunogenic viral polypeptides and viral-like particles (VLPs). Methods for producing Norovirus- or Sapovirus-derived multiple epitope fusion antigens or polyproteins and immunogenic compositions comprising one or more immunogenic polypeptides, polynucleotides, VLPs, and/or adjuvants are also described. The immunogenic compositions of the invention may also contain antigens other than Norovirus or Sapovirus antigens, including antigens that can be used in immunization against pathogens that cause diarrheal diseases, such as antigens derived from rotavirus.