The Criminal Justice and Public Order Act gave police new power to attach conditions to defendants' bail in order to reduce the number of defendants detained in custody overnight to ensure appearance at magistrates' courts, as well as to increase control over defendants on police bail to prevent reoffending or absconding. Although the police welcomed this power, there was some concern that it might be abused. The study reported in this article examined how one police force was using its power to attach conditions to bail. Data collection was done through a questionnaire sent to custody officers and an examination of a sample of police records on post-charge bail decisions. The study found that the introduction of police conditional bail had reduced the number of defendants detained in police custody, but also the number of defendants granted unconditional bail. This latter finding suggests that some "net-widening" has occurred. Differences were found between police stations and Criminal Justice Units in the use of conditions and how their use was justified. The study concluded that although the law relating to police bail provides a broad framework for structuring police decision making, it also provides the opportunity for informal police practices and policies to shape the operation of the police bail process. 8 tables and 28 references