The ongoing Consumer Expenditure Survey (CES) provides a continuous flow of information on the buying habits of American consumers and also furnishes data to support periodic revisions of the Consumer Price Index. The survey consists of two separate components: (1) a quarterly Interview Survey in which each consumer unit in the sample is interviewed every three months over a 15-month period, and (2) a Diary Survey completed by the sample consumer units for two consecutive one-week periods. The Diary Survey contains expenditure data for items purchased on a daily or weekly basis. Participants from consumer units, which are roughly equivalent to households, are asked to maintain expense records, or diaries, of all purchases made each day for two consecutive one-week periods. Diaries are designed to record information on small, frequently purchased items such as food, beverages, food consumed away from home, gasoline, housekeeping supplies, nonprescription drugs and medical supplies, and personal care products and services. Information is also elicited at the end of the two-week period on work experience, occupation, industry, retirement status, member earnings from wages and salaries, net income from business or profession, net income from one's own farm, and income from other sources. The unit of analysis for the Consumer Expenditure Surveys is the consumer unit, consisting of all members of a particular housing unit who are related by blood, marriage, adoption, or some other legal arrangement. Consumer unit determination for unrelated persons is based on financial independence. The Consumer Unit Characteristics and Income (FMLY) files supply information on consumer unit characteristics, consumer unit income, and characteristics and earnings of the reference person and his or her spouse. Member Characteristics (MEMB) files contain selected characteristics for each consumer unit member, including reference person and spouse. The Detailed Expenditures (EXPN) files present weekly data on expenditures at the Universal Classification Code (UCC) level, while the Income (DTAB) files contain weekly data on income at the UCC level.