Rational-choice theory locates criminal behavior within situations where individuals are stimulated to make decisions that lead to behaviors designed to meet the individual's emotional and/or material needs. In applying this theory to an individual's accessing and manipulating the Internet for child pornography, the authors consider the concepts of search, precriminal situation, and opportunity. Links between this approach and a related cognitive-behavioral therapy (CBT) model of offending are explored. "Search" involves an individual's looking for a suitable precriminal situation that will result in the commission of an offense. In the case of Internet child pornography images, this involves searching the Internet for images of child sexual abuse. "Precriminal" situations are the circumstances immediately preceding and associated with the criminal event that make the offense more or less difficult, risky, or profitable. In the case of Internet child pornography, an individual assesses the risks and difficulties involved in searching for and finding child pornography. "Opportunity" refers to the existence of a setting in which risks of adverse consequences for an act is reduced to the point that an offense is likely to occur. The Internet offers an opportunity for anonymity and a reduced likelihood of being observed or detected while involved in child pornography. CBT suggests the importance of structuring environments that manipulate the thinking that precedes behavior. In the case of the criminal use of the Internet, this suggests prevention tactics that will make it increasingly difficult for child pornography to be displayed and viewed on the internet. Practical suggestions are offered. 9 notes and 33 references