Expensive security systems are easily manipulated by even the most amateur thieves, and stealing continues in libraries even though some States have declared mutilation or theft of library books a criminal act. A multiple-choice questionnaire was sent to academic libraries in the Mountain Plains region (Colorado, Kansas, Nebraska, Nevada, North Dakota, South Dakota, Utah, and Wyoming). Study of the 23 replies reveals 2 ways of regarding electronic detection systems. One group uses them only as a tool to prevent uncirculated materials from leaving the building, an extension of the circulation system. The second group uses electronic detection as more, as a means of apprehending thieves. Half the libraries replying to the questionnaire do not identify thieves and have no real commitment for apprehending and punishing them. The other half identifies thievery attempts and keeps records, taking punitive action. The data imply that librarians probably do not think theft of their books is a crime. It is concluded that librarians do not yet investigate what is legally possible to stop theft, and seem to tolerate it. (Author abstract modified) 6 tables and 14 endnotes.