Combining information from literature and indepth interviews with 11 arrested professional thieves and also with police officers, the study found that the thieves' dominant modes of operation followed traditional methods. However, some professional thieves were adjusting to hardening security measures and were beginning to use more dangerous ways to commit thefts. Most thieves in Lahti adjust to increased security measures by changing targets. They choose new, less protected types of targets, such as neighboring communes, smaller stores and shops, cars, private residents, and also individuals. About 50 references are provided. (Author summary modified)