Used principally in parking enforcement, the hand-held units enable officers to issue computer-generated citations and simultaneously check the vehicle for outstanding (unpaid) tickets. These rugged, weather-resistant systems contain enough memory to hold as many as 40,000 records, such as records on scofflaws or stolen/wanted vehicles. They can be operated in a search mode, enabling an officer to check vehicle tags without issuing a citation. The system generates data on an officer's daily activity for later management analysis. In addition to parking and traffic enforcement, the units can also be used for field interviews, code enforcement, utility meter reading and other non-law enforcement functions. The article describes advantages and limits of the units, and relates operational experiences with the system. There is a brief list of vendors of hand-held computers that have application to law enforcement and other justice agencies, a photograph of one type of hand-held computer, and a sample of a ticket generated by such a unit for the California Highway Patrol.