A Conneticut-born Jew, he had one sister named Joanie who died as a result of a house fire involving a popcorn machine(though read Sabine's The Largest Colonial Building in the World for a different take on that saga). His grandfather was a survivor of Birkenau, which was the main death camp at Auschwitz during WWII, and his father died the night of the Illinois primary. His mother is still alive and sends him shoes with slippery soles. He scored a 760 SAT verbal score, and is a graduate of Harvard and Yale, as well as being a Fulbright scholar. While he graduated from law school, he never practiced. He's arrogant, full of himself, and cocky (yes, that's redundant but it's for emphasis) though he's amazingly sensitive when he wants to be. Josh broke into politics as floor manager to the House minority whip and Chief of Staff for Congressman Earl Brennan. Interestingly, he worked on Hoynes' presidental campaign, before ditching him for "the real thing" he saw in Bartlet.

He brought Sam onto the campaign, and hired Donna Moss as his assistant (though it can be argued that she hired herself). Josh dated Mandy, (and he insults Donna's taste in dating partners!) and plays basketball, golf, and occasionally jogs - though he doesn't like it very much and gets rather red and sweaty.

He was shot in Rosslyn, Virginia, when teenage skin-heads attempted to assassinate Charlie. His lung collapsed and his artery was ruptured, and he spent a lot of his recovery time reading about theoretical physics. As a result of that accident, he has problems listening to music, Yo-yo Ma causes him to go into convulsions, and he has this thing with therapists named Stanley.

He has smoked pot using a potato, though never thought of using an eggplant. He also has a delicate system, can't hold his alcohol, is learning American Sign Language, can quote Jefferson when it suits him, and often behaves like an over-grown frat boy (though it should be noted that even at his worst, he acts like an intelligent frat boy, which is more than we can say for the idiot currently occupying the official white house). He holds a grudge, has a talent for wit and hyperbole and crossing the metaphorical line.