The growing interest in ontologies is concomitant with the increasing use of agent systems in user environment. Ontologies have established themselves as schemas for encoding knowledge about a particular domain, which can be interpreted by both humans and agents to accomplish a task in cooperation. However, construction of the domain ontologies is a bottleneck, and planning towards reuse of domain ontologies is essential. Current methodologies concerned with ontology development have not dealt with explicit reuse of domain ontologies. This paper presents guidelines for systematic construction of reusable domain ontologies. A purpose-driven approach has been adopted. The guidelines have been used for constructing ontologies in the Experimental High-Energy Physics domain.