Kaplan joined the crew of Six Feet Under during the first season in 2001 as a supervising producer. He scripted two episodes of the first season – "The Foot" and "The New Person". He was promoted to co-executive producer for the second season in 2002 and wrote a further two episodes – "The Invisible Woman" and "The Secret". He remained a co-executive producer for the third season in 2003 and wrote a further episode entitled "The Trap". He was promoted to executive producer for the fourth season in 2004 and wrote another episode "The Dare". He served as executive producer during the fifth and final season and wrote his last episode "The Silence". Kaplan wrote seven episodes in total for the series.
No One You Know: A Collection of Cartoons (1999) Simon & Schuster ISBN 068485919X
The Cat That Changed My Life: 50 Cats Talk Candidly About How They Became Who They Are (2002) Simon & Schuster ISBN 0743219449
This Is A Bad Time: A Collection of Cartoons (2004) Simon & Schuster ISBN 0743252187