Approximately 90 percent of the defendants in the sample were involved in property, violent, or sexual offenses, predominantly of a serious nature. Roughly a third of the defendants in both cities made written statements which could be regarded as full confessions, and only about one-quarter reached the court without some type of damaging statement recorded against them. Over 90 percent of the defendants who made written statements to the police in Birmingham and 76 percent in London pleaded guilty at trial. Forensic evidence was either not available or not important in 95 percent of the cases. No more than 2.4 percent of defendants in Birmingham and 5.2 percent in London were acquitted at trial, having made written confessions to the police. In most cases, important evidence derived from the interrogation was obtained at the police station. Most interrogations lasted less than 2 hours, and only about 2 percent continued beyond 4 hours. The younger the defendant, the more likely he or she was to confess. Also, recidivists were more likely to make verbal and written statements than persons without prior convictions. There was no consistent variation in confession rates according to type of offense. The accused's statement was considered to have had no real bearing on the strength of the prosecution's case in almost half the cases, but in 20 percent it was considered that the prosecution's cases would be fatally weakened without the defendants' statements. In light of these findings, the criminal justice system should ensure that confessional evidence is obtained under conditions that do not breach Judges' Rules regulating police interrogation. Tables, graphs, and 44 references are supplied.