Born March 31, 1939 in Wakefield, Massachusetts, Horovitz was the son of truck driver Julius Charles Horovitz and his wife, Hazel Rose Solberg. He began writing in his early teens, penning a novel titled Steinberg, Sex and the Saint that he submitted to Simon and Schuster at the age of 13. But after attending a production of Lorraine Hansberry's "A Raisin in the Sun," Horovitz shifted his focus to playwriting. In 1958, the 17-year-old wrote his first drama, "The Comeback," which was produced two years later at Suffolk University. More plays soon followed, which helped to earn him a fellowship in playwriting at the Royal Academy of Dramatic Art in 1961. Horowitz returned to the United States in 1963, but revisited London in 1965 as the first American writer to serve as playwright-in-residence at the Royal Shakespeare Company's Aldwych Theatre. Two years later, he scored his first hit with "Line" (1967), an absurdist drama about a quintet of people waiting in a line for an unspecified event. The original production at the prestigious Café La MaMa featured Horovitz and a then-unknown Richard Dreyfuss in the cast. The play itself went on to become the longest-running Off-Off-Broadway show in American history, with a revival playing continuously at the 13th Street Repertory Theater for over four decades starting in 1974.In the late 1960s and early '70s, Horovitz enjoyed a string of critical and box office hits, beginning in 1968 with the "The Indian Wants the Bronx" and "It's Called the Sugar Plum." The one-act plays -- the former about an Indian immigrant who is set upon by a pair of New York hoods, and the latter about two romantically involved college students linked to a hit-and-run accident -- launched both the Off-Broadway Astor Place Theatre, which chose the two plays as its first production, and the careers of Al Pacino, Jill Clayburgh and John Cazale, who played the lead tough, the college student's girlfriend and the immigrant, respectively. Both plays won the Obie Award, minting Horovitz as a major new voice in Off-Broadway theater with a particular talent for merging gritty ultra-realism with elements of fantasy and social metaphor: in "Rats" (1968), a pair of rodents fight for the right to bite an infant, while "Morning, or Chiaroscuro" (1969), a mysterious medicine turns an African-American family into Caucasians. The popularity of these works led to a second career as a screenwriter for film and television projects, including the counterculture drama "The Strawberry Statement" (1970), which won the Prix du Jury at the 1970 Cannes Film Festival. After gaining his Ph.D at City University of New York in 1971, Horovitz developed a transcontinental career, writing new plays, screenplays and teleplays throughout the 1970s while also directing translations of his work in France, where he eventually became the most-produced American playwright in French history, and Italy. In 1973, he began "The Wakefield Plays" (1973-1986), an ambitious seven-party play cycle comprised of two connected sets of one-act stories: the "Quannapowitt Quartet" and the "Alfred Trilogy," both of which concerned intense personal dramas set in small-town Massachusetts. While completing this sprawling project, Horovitz also penned his first novel, Capella (1973) and numerous stand-alone plays, including "The Primary English Class" (1975), which starred Diane Keaton in its original theatrical run; "Sunday Runners in the Rain" (1976); "The Widow's Blind Date" (1978) and "A Christmas Carol, Scrooge and Marley" (1979), adapted from the Charles Dickens novel. He also found time to found The New York Playwrights Lab in 1975 and the Gloucester Stage Company in 1979. In 1982, Horovitz drew parallels to his own life with the screenplay for the comedy "Author! Author!" with Al Pacino as a playwright juggling the responsibilities of his large family with the pressures of a new play. A second play cycle, alternately known as "A Trilogy," "Growing Up" and "The Sault St. Marie Trilogy," occupied much of the mid-1980s before scoring a major hit with "Park Your Car in Harvard Yard" (1991), a potent two-person drama about the relationship between a dying teacher (Jason Robards) and a former student (Judith Ivey) who became his housekeeper. Ivey received a Tony Award nomination for her performance in the play, which earned Horovitz some of the strongest critical praise of his career. He also worked on several high-profile film projects during this period, including a 1997 TV adaptation of his 1986 play "North Shore Fish" for the Hallmark Hall of Fame, and the historical drama "Sunshine" (1999), which earned three Golden Globe nominations, including Best Motion Picture - Drama. After penning the screenplay for TNT's "James Dean" (2001) about the iconic actor, he made his directorial debut with the documentary "3 Weeks After Paradise" (2002), which recounted his family's experiences after the September 11, 2001 attacks on New York City. In 2009, Horovitz's 70th birthday was celebrated with a slew of international tributes, including his appointment as a Commander of the Order of Arts and Letters by the French government. The NYC Barefoot Theatre Company also initiated the yearlong 70/70 Horovitz project, for which 70 of his plays were either performed or read by theater companies around the globe, including the national theaters of Ghana and Nigeria. After publishing his memoirs, Un New Yorkais a Paris in 2013, Horovitz fulfilled a long-standing ambition by directing a feature film adaptation of his 2003 play "My Old Lady." The British-American production starred Kevin Kline and Maggie Smith, and was produced by his daughter, Rachel, who had previously overseen such major productions as "About Schmidt" (2002) and "Moneyball" (2011).