After nearly 30 years of commercially available frozen-thawed (FT) boar sperm, it has not received widespread acceptance for commercial breeding in the swine industry. Currently, less than 1% of all artificial insemination in the swine industry is performed using FT semen. This is a result of the suboptimal fertility rates obtained when FT semen is used. Boar semen has proven difficult to cryopreserve. The sperm cells are extremely vulnerable to cold shock and undergo a capacitation-like process during cryopreservation, termed cryocapacitation, leading to decreased fertility. In this dissertation, we compared capacitation and cryocapacitation and examine the effects of seminal plasma (SP) on these processes, identified protein components of SP that are responsible for the suppression of capacitation and cryocapacitation, and characterized the Crisp family of genes as well as the function of these proteins to regulate capacitation and cryocapacitation. We demonstrated that SP has a regulatory effect on both capacitation and cryocapacitation and provided evidence for the proteins in SP being responsible for this result. We have also shown the similarities between the two processes. The major results of this dissertation are twofold. First, cryocapacitation results in a similar endpoint as capacitation as defined by the competency to undergo an acrosome reaction. We hypothesize that the pathways that each process takes are different. Second, specific proteins in SP can alter and/or regulate these pathways. We have shown that members of the spermadhesin protein family and not the Crisp family of proteins are involved in this inhibition in the boar.