Contracts are a tool used by software engineers to validate assumptions made during the development of software systems. In the world of higher-order programming, higher-order contracts serve as a compositional mechanism to ensure that each function application satisfies the argument and result predicates that form a higher-order contract. The usual implementation of contract systems include a contract monitoring component in the runtime. Most formal incarnations of contracts treat the monitor as a transparent component with only one benign effect: terminating programs that violate their contracts. The monitoring of contracts is, however, far from being this benign: it may completely changed what part of the program gets evaluated and in what order. Such effects were noticed earlier in the context of lazy languages but their full impact has not been fully appreciated. In the talk, contract properties will be framed in a new context in which the monitoring of contracts is viewed as an explicit effect.