This volume contains 9 research articles by leading scientists on topics in universal algebra, lattice and order theory, classical algebra and applications of algebra. The book continues the series "Contributions to General Algebra", Volumes 1-19, published from 1979 to 2010. The volume consits of papers presented at the 81st Conference on General Algebra, February 3-6, 2011, in Salzburg, Austria. All accepted scientific papers have been refereed by an international board.This book is of interest to research workers in the field of algebra and should be useful as a reference book for many mathematicians.