Adam Carlson was probably a boy associated with Beth Ann Nelson, perhaps her schoolmate at Mt. Pleasant High School. He was well-built and was a jerk, which means that he was probably a high school jock. It seems that Beth admired his muscles and that he was smart. His phone number is 555-6171.
His name is seen in Beth Ann Nelson's Address Book which indicates that she used to be interested in him, but it is also struck out. She was either disappointed by him being a jerk, or she shifted her interest to Merrick Campbell, since his name is written in the facing page.
Marrianne preferred Adam to Merrick, and he had a friend she considered cute.