During the years 1987 and 1988 we published a series of articles on the molding of thermoplastics materials in the magazine British Plastics and Rubber (B P & R). These articles were very well received and we also received a large number of requests for reprints. In order to cater for what is obviously a need in the thermoplas- tics molding industry, we therefore brought the information together and produced it in the form of a book. We can only hope that it serves you well and that you find the information useful. We in turn would like to thank the editor of the magazine B P & R for helping us in this matter. Thanks are also due to our many friends and colleagues throughout the molding industry for their useful help and advice, in particular the company Moldflow (Europe) limited deserve a special mention as they allowed us to extract information from their extensive data base.