This monograph is concerned with the application of temporallogic to the areas of message passing and time-criticalsystems. Apart from the practicaluse of temporal logic forthese two application domains, the book also incorporatespure fundamental studies on temporal logic.The motivation to study message passing and time criticalsystems stems from their importance in practice. Messagepassing is one of the most important means of interprocesscommunication in distributed systems, either on a highlevel, as in telecommunications applications, or on a lowerlevel, as in implementations of languages like Ada. As fortime-critical systems, among the growing number of real-timeapplications there are some highly critical systems such ascomputer controlled chemical plants and nuclear powerstations.The monograph shows how standard temporal logic can be usedfor the specification of message passing systems, anddevelops a special temporal logic for reasoning aboutquantitative temporal properties.The main application areais that of distributed real-time systems.