Volumes dedicated to a single topic have been released, under the title Uncle John Plunges Into..., for example: history, presidents, and the universe.
Currently, the institute publishes three books a year; a "classic" reader, and two "plunges into" editions, one for a location such as a U.S. state, and another of a specific topic.
Their volumes contain information on subjects such as quotes, dumb criminals, palindromes, anagrams, urban legends and hoaxes, failed inventions, the history of everyday things, and accidental discoveries, as well as articles on pop culture and 'celebrities' such as Emperor Norton (see Features).
After the initial four books, the BRI decided that it would publish further volumes under its own label, and Uncle John's 5th Bathroom Reader was released in October 1992; notable for a revised writing style, more and longer articles, and the introduction of new recurring features, Uncle John's 5th set what would become the standard design for every book going forward.
In 1995, the millionth copy of the series was sold, and to celebrate the milestone, the BRI released an eighth volume, The Best of Uncle John's Bathroom Reader.
[3] The series continued to be published by Portable Press, and the Javna brothers were described by Bookriot as not being directly involved with the publication of the Bathroom Reader books as of 2022.
These editions focused on such things like individual U.S. states, history, national parks, Hollywood, television, the U.S. Armed Forces, the environment, etc.