It describes 245 of the worst property offenders in the city, as identified by police, and their accomplices (both experienced and novice criminals). Of the 245 criminals, about 60 percent were active thieves. These criminals were mostly male, of median age 29 years, with prior criminal records. Most had temporary work histories, and many received welfare benefits. Most criminals were older than accomplices, tended not to be born in Lahti in comparison to the other groups, and had severer criminal histories. Evidence suggests that there is a relatively strong underworld based on professional stealing in Lahti. Study data and illustrations are supplied. (Author summary modified)