This publication is part of a continuing effort by the Statistics Division to develop comprehensive recommendations for national work on price and quantity statistics. It stems from the discussion of price and quantity comparisons in System of National Accounts and Guidelines on Principles of a System of Price and Quantity Statistics. It examines alternative strategies for the measurement of price and quantity in external trade and considers sources of data; approaches to measurement; major problems of pricing; the problem of aggregation; some tentative solutions; and strategies for compiling index numbers. An annex on coverage and structure of index numbers in external trade is included, as is a list of references.