The adhesion behavior of blends of polybutadiene (PB) and tackifiers was investigated. The peel strength was found to be significantly dependent on blend composition, and a maximum strength behavior was observed for all blend systems. The tack mechanisms were proposed to explain the observed adhesion behavior. The position of the glass transition temperature is related to where the highest tack appears for the miscible blend; for the partially miscible blend the dispersed phase plays an important role in determining the maximum adhesion, and the critical size of the dispersed phase and the T-g of the tackifier phase together determine what concentration of tackifier gives the maximum tack. For the immiscible blends, the maximum adhesion is controlled by both the surface glass transition temperature and the critical diameter of the domains of the tackifier phase.