The aim of this study was to examine the empirical connections of three phenomena among the Finnish population: (1) the level of knowledge on the crime situation and the criminal justice system; (2) the general punitive attitude and (3) sentence decisions in certain concrete crime cases using vignettes. The same vignettes were shown to professional judges to study the punitive gap between laypeople and judges. The research subjects are a representative sample of the population (N = 1251) and district court judges (N = 192). The research resulted in four main findings: (1) a higher level of knowledge among laypeople mitigates their punitive attitudes, (2) information included in the case vignettes is associated with the sentence decisions of laypeople in different ways, depending on the characteristics of the case; punitive gap varies greatly, (3) level of knowledge is, in general, a poor predictor for the severity of the sentence decisions of laypeople and (4) the general punitive attitude is, at best, a weak predictor for the severity of sentence decisions of laypeople. In conclusion, laypeople's decisions are probably affected partly by the same legal factors as the professional judges' decisions and partly by attitudes that are expressly related to features of the cases in question.