During 9-11 September 1992, the Scientific Council held a Special Session on "State-of-the-Art in Fish Assessment: a Tutorial/Workshop on Calibration Methods and Their Practical Use" at the NAFO Headquarters, Dartmouth, Nova Scotia, Canada, with R. K. Mohn (Canada) and R. Cook (EEC-United Kingdom) as co-conveners. For use during this tutorial/workshop R. K. Mohn prepared a workbook titled Introduction to Sequential Population Analysis and R. Cook prepared a working paper on ICES VPA Tuning Methods, while some additional working papers were circulated during the sessions. At its meeting of 14-18 September 1992, the Scientific Council agreed that the ICES VPA tuning methods be included in a revised workbook and that all materials contained in the other working papers be incorporated in a publication of a single volume of NAFO Scientific Council Studies. The tutorial material prepared by the authors now form the body of this Workbook, and the other working papers are appended.