In this paper we describe the Chasqui approach to the construction of repositories of learning objects (LO) in specific knowledge areas. This approach is the result of our experiences in the virtualization of academic museums at the Complutense University of Madrid (Spain) as well as of some experiences in the virtualization of the campus of this university. This approach promotes a close collaboration between two kinds of actors: domain experts (e.g. researchers and lecturers) and developers. This collaboration results in (i) the definition of a suitable model for the LO in the domain of interest, (ii) the construction by developers of a domain-specific tool for authoring LO conforming this model, and (iii) the population of the repository by domain experts using this tool. The domain specific LO models and the domain specific tools based on these models facilitate the production and maintenance of the repositories and the exploitation of the educational potential of the resources us...