Concept or Galois Lattices (CL) provide a productive framework for a variety of problems that arise in Knowledge Discovery in Databases (KDD). This paper introduces this special issue of Applied Artificial Intelligence devoted to applications of Concept Lattices for KDD (CLKDD). The papers in this volume come from a call for papers issued after the first International Workshop on Concept Lattice-based Theory, Methods and Tools for KDD held in July 2001 at Stanford University. Another special issue devoted to algorithms and methods of CLKDD will appear in the Journal of Experimental and Theoretical Artificial Intelligence.