Eureka school board president Eric Franz explained that a "significant number of students" had objected last January to passages in the famously earthy Miller's Tale.
A small group of 17-year-olds refused to join classroom discussions, saying they were embarrassed by the material.
When the students consequently received low grades from teacher Nancy Quinn, their parents complained, first to the teacher and then to the board. The school responded by asking Mrs Quinn to "de-emphasise" any sexual material, said Mr Franz.
This autumn it put a hold on its Chaucer teaching while the board examined versions of The Canterbury Tales considered more suitable for sensitive mid-Western teenagers.
The spotlight has turned suddenly on Eureka, a town of about 5,000 people 20 miles east of Peoria, where former president Ronald Reagan went to college. Local press and big city radio stations have been calling Mr Franz for comment. He feels the attention is undeserved.
"I'm not an educator, I'm an accountant," he said. "All the people I've talked to said Chaucer is a very good author. We simply requested that a different edition be used.
"We are not trying to censor anything. We are not banning books from Eureka. We are trying to find appropriate material for our students."
There is a well-documented history of censorship in US classrooms, and The Tales have raised hackles before. "Pro-family" groups and religious conservatives have challenged everything from Little Red Riding Hood (she was carrying wine) to the American Heritage Dictionary.
Mr Franz extolled Eureka as a home from home based on family values. "It's a wonderful place to raise kids, I'm just tickled to death with it. I'm not from here, but you couldn't run me off with a stick."