Palabras clave: Bibliotecas universitarias; Catá-logos en línea; Interfaces de descubrimiento; Metabuscadores; Sistemas Integrados de Gestión Bibliotecaria. Abstract Redefining the Catalog. Expectations on User-Centered Discovery Interfaces Mª Luisa Alvite DíezThe continuous developments of OPACs still have not succeeded to constitute an optimal search tool for the overall available resources on a twenty-first century academic library. The academic community perceives OPAC as an ineffective tool and far from the web services that they usually employ. The attempts to develop OPACs and incorporation of metasearch products on the websites of academic libraries are reviewed. The paper explores the increasing implementation of discovery interfaces, reviewing studies on these platforms, its functionality and implementation on one side, and usability analysis on the other. The current state of search tools in the Spanish academic libraries is finally examined, deducing of this exploration the clear trend towards the implementation of single search tools.