This paper proposes the notion of Specification-Carrying Code as an interaction mechanism for self-assembly of au- tonomous decentralised software components. Each au- tonomoussoftware entity incorporates more informationthan its operational behaviour, and publishes more data than its signature. The idea is to provide separately, for each en- tity, a functional part implementing its behaviour - the tra- ditional program code; and an abstract description of the entity's functional behaviour and necessary parameters - a semantic behavioural description under the form of a for- mal specification. Interactions are exclusively based on the specifications and occur among entities with correspond- ing specifications. In the case of autonomic computing sys- tems, in addition to functional aspects, the specification may carry a semantic description of non-functional information related to self-management. This paper presents the prin- ciples of the Specification-Carrying Code paradigm, the as- sociated Service-Oriented Architecture, and it explains how self-managed systems can benefit from this paradigm.