His mother was mentally ill, his father died in Richard's childhood, he temporarily stayed in a local orphanage, and was mainly raised by his grandmother.

He graduated from Jefferson High School in Portland, Oregon, then enlisted in the U.S. Army, was deployed to the Vietnam War, and returned in 1970 almost completely deaf.

This attitudinal training program aimed to reduce congressional resistance to AIDS being covered by the Americans with Disabilities Act (ADA).

[9][11] Pimentel started in 2008 with designing and implementing a training program for the employers of disabled veterans returning from Iraq and Afghanistan focusing on PTSD and traumatic brain injuries.

According to Milt Wright & Associates' website, Pimentel has been the Chairperson of VACOR, the Department of Veterans Affairs' Civilian Advisory Committee for Rehabilitation.