Immunogenic compositions containing phospholipid adjuvants, including microparticle and emulsion compositions. According to one aspect of the invention, an immunogenic microparticle composition is provided comprising: water; a polymer microparticle; an antigen adsorbed to the microparticle; and a phospholipid compound, e.g., a synthetic phospholipid compound comprising: (i) one or more phosphoryl groups independently selected from a phosphato group and a phosphodiester group; (ii) a plurality of linear alkane groups. According to another aspect of the invention an immunogenic emulsion composition is provided that comprises: water; a metabolizable oil; an emulsifying agent; an antigen; and a phospholipid compound, e.g., a synthetic phospholipid compound like that above. The emulsion composition is an oil-in-water emulsion having oil and aqueous phases, in which the oil phase is in the form of oil droplets, substantially all of which are less than 1 micron in diameter.