The invention relates to immunostimulatory oligonucleotide compositions. Theseoligonucleotides comprise an immunostimulatory octanucleotide sequence. Theseoligonucleotides can be administered in conjunction with an immunostimulatorypeptide or antigen. Methods for modulating an immune response uponadministration of the oligonucleotide are also disclosed. In addition, an invitro screening method to identify oligonucleotides with immunostimulatoryactivity is provided.