What is the Consumer Price Index (CPI)? The CPI is an index monitored by the Bureau of Labor Statistics (BLS). Each month, BLS collects data from various urban areas throughout the country on prices of a fixed market basket of goods such as food, clothing, shelter, fuels, prescriptions, transportation fares, medical fees, and other goods and services that people purchase for day-to-day living. Keeping up to date on the CPI is important as a predictor of coming wage increases and of employees' need for greater income.