This was written by Brian Wilson and frequent collaborator Gary Usher, and released on the Beach Boys’ 1963 album Surfer Girl. Later that year it was the B-side of their Be True to Your School single. In My Room peaked at number 23 in the US while Be True to Your School got to No 6. I’m not sure why, but Rolling Stone magazine placed In My Room at 212 on its list of greatest songs of all time.
Here is a lovely live performance from 1964. They really could sing.