Even if you don't know an adult student's lexile score, you can still look for books by grade level equivalent based on their last TABE test, and add information about the books the student normally reads, like they are usually at my level, they are usually too easy, or they are usually too difficult.
Even though the results are books for children, you can still find something with central adult characters by reading the one sentence summaries in the list of results. The interest level is also indicated.
For example, I put in 4th grade as the reading level, and I said that the books I read in school are usually just right for my level. On the next screen I selected nature as one of my topics, et voila, I found The Heart Calls Home, which is a book I would love to read as an adult:
"Obi tries to make a new life on a S. Carolina island, while waiting for his soul mate who is studying up North."
- Grade level: 4
- Lexile level: 650L
- Ages: 12 to 17 (interest level)
- Page count: 175
- Publisher: Walker and Company, 1999
- ISBN: 0802786367
- ISBN13: 9780802786364