New Jersey native, Pelphrey became involved in his high school theater program, which led him to pursue conservatory theater training at Rutgers University. A CBS casting associate saw him in a school-related theater showcase, and a few months later, Pelphrey met with GL Casting Director Rob Decina. Pelphrey remains close to his mom, Laurie, and his younger brother, Bobby, and often returns to New Jersey to visit them. At the set, Pelphrey has formed tight friendships with many co-stars, including Doug Hutchison (Sebastian), with whom he journeyed to London for New Year's to ring in 2005.
He attended a performing arts program at Howell High School with Jason Allentoff, Cheryl Kurn and Derek Gross.
He graduated Howell High School in 2000.
He then graduated Rutgers University in 2004 with a Bachelor's Degree in Fine Arts.