This paper presents the main features of XFL3, a new language for fuzzy system specification, which has been defined as the starting point for the 3.0 version of our fuzzy system design environment, Xfuzzy [1]. Its main advantages with respect to its precursor, XFL [2], are its capability to admit user-defined membership functions, parametric operators, and linguistic hedges. Taking this language as the basis, different fuzzy system development tools are being implementing, which are also summarized briefly.This work has been partially supported by the Spanish CICYT Project TIC98-0869 and the FEDER Project (Nº 1FD97-0956-C3-02).Peer reviewed