This invention, in one aspect, relates to synthetic immunoreactive peptides. These peptides are approximately 20-25 amino acids in length which are portions of the N termini of the M proteins of the most prevalent United States (U.S.) Group A Streptococcus (GAS) serotypes. At least some of the synthetic peptides can be recognized by M type-specific antibodies and are capable of eliciting functional opsonic antibodies and/or anti-attachment antibodies without eliciting tissue cross-reactive antibodies. In another aspect, it relates to compositions or vaccines comprising these synthetic serotype-specific peptides, including polypeptides and proteins. The invention may also be isolated antibodies which are raised in response to the peptides, compositions or vaccines. The invention further relates to kits for using the peptides, compositions, or antibodies. In still further aspects, the invention also relates to methods for using the peptides, compositions, vaccines, or antibodies and methods for tailoring vaccines.