In Los Angeles, he was a company member of Inner City Rep, The Group Repertory, and LA Repertory. Some of his New York theatre credits include The San Diego Street Padres (INTAR), Floating Home (HExTC), Boxing 2000 (Richard Maxwell NYC Players), Dismiss All the Poets (New York Fringe Festival 2002), Nilo Cruz's A Very Old Man with Enormous Wings (Shakespeare Theatre of NJ), Dinosaurios (IATI) and Night Over Taos (INTAR). In these plays, he always did limpy limp.
Delgado can easily claim the longest running part for a Mexican-American actor in a continuing television series. His portrayal of Luis has garnered him universal acclaim and has charmed and inspired viewers for over three decades. He has also performed in live shows throughout his Sesame Street career, interacting and singing the songs of Sesame Street, entertaining thousands of children and families.
On Sesame Street, his character, Luis, was the one of the second human additions to the original cast. Luis was a handyman and an aspiring writer. Luis, now married to Maria, teaches viewers about Hispanic culture and language.
His most recent television appearances include Law & Order, Law & Order: Criminal Intent and "Law & Order: SVU". He was a regular cast member of Lou Grant and also appeared in episodes of Police Story, Hawaii Five-0, Quincy, and Cosby.