Dr William Pena was born in Santo Domingo, Dominican Republic where he graduated from medical school at Universidad Autonoma de Santo Domingo in 1982. He practiced and taught in medical school. In 1990 he did his internship at Bronx-Lebanon Medical Center and went on to complete his residency in internal medicine at Mount Auburn Hospital, Harvard medical school where he stayed as faculty from 1993 to 2001.
In 2002 he moved to Florida and practiced at mercy Hospital until 2003 where he was presented with the physician recognition award of the year. Since 2003 he has been practicing in the memorial hospital system in south Broward. He is presently the chief of medicine at Memorial hospital Miramar.