Wordprocessors and other information technology are now used on a daily basis by a wide variety of people. Although interfaces have been made much easier for novices to learn, very little is still known about how users progress from novice to expert performance. This volume is based upon a large continuous field study - seven years of editor use by 4000 students at Sydney University. It assesses the results and argues that the process of change in long term HCI appears to be constrained by three pillars: an essentially static measure of vocabulary use; continuous growth through exploration; and specialization between methods via crossovers. This book will be of interest to HCI researchers and designers, computer scientists, information specialists, cognitive scientists, academics and postgraduate students.