Juvenile arrest, i.e., detention of up to 4 weeks, was conceived as a sanction between incarceration and educational measures, to be applied to youths committing petty offenses who evidenced sound personalities. These youths would reverse their criminal involvement as a consequence of the detention experience. The concept was assumed to exclude juveniles from deprived backgrounds considered at-risk of continued criminality. Critics contend that juvenile arrest's deterrent effect cannot be proven, since the type of youths detained are likely to refrain from further delinquency even without this form of punishment. Furthermore, it serves no pedagogical purpose and has stigmatizing effects. A steady decrease in the percentage of juvenile arrest sentences in the 1970's evidences justices' response to these critiques. The existing detention centers' limited capacity has also served to keep the absolute numbers of arrested juvenile constant. A 1979 study examined the sentencing practices by which youths are committed to juvenile arrest. A 170-item questionnaire was filled out on personal and background variables of a total of 2,006 arrested juveniles in Hamburg, Nordhesses, Oberbayern, and Munich. Data analysis revealed that juvenile courts apply the arrest sentence especially to troubled youths who appear to be most at risk. Social marginality correlated highly with both frequency and length of imposed juvenile arrest. Arrests of longer duration especially appeared to be motivated by evidence of disorder in the juvenile's life style or circumstances. Only in Hamburg were long-term juvenile arrest sentences not used as a mere deterrent, but incorporated positive stimuli and assistance in resolving the juveniles' problems. Tabular data, footnotes, and a bibliography are given.