Sebastian Joseph-Day hails from Stroudsburg, Pennsylvania where he played at Stroudsburg High School under head coach Joe Bernard. As a senior, Joseph-Day recorded 40 tackles and a whopping 17 tackles for loss to help lead his team to their second-consecutive Mountain Valley Conference Championship in 2012.
As a three-star recruit by Rivals.com and ESPN.com, Joseph-Day chose to stay on the east coast to play for the Scarlet Knights of Rutgers.
Joseph-Day earned playing time as a true freshman, but an injury forced him to redshirt just one game. In 2014, he played a role in all 13 games for the Knights but finished with just three tackles.