Protein folding and aggregation is the process by which newly synthesized proteins fold into the specific three-dimensional structures defining their biologically active states. It has always been a major focus of research in biochemistry and has often been seen as the unsolved second part of the genetic code. There is also much emphasis on computational methods and studies of protein aggregation which have really flourished in the last decade. It includes chapters in the areas that have witnessed major developments and are written by top experts including:computer simulations of folding, fast folding, single molecule spectroscopy, protein design, aggregation studies (both computational and experimental).