The purpose of this technical report is to provide documentation of all programming and statistical activities involved in the construction of the price and purity series presented in Price and Purity of Illicit Drugs: 1981 Through Second Quarter of 2003, the main report prepared for the Office of National Drug Control Policy (ONDCP). The technical report contains information on the exact steps taken to acquire the data from the Drug Enforcement Administration (DEA) System to Retrieve Information from Drug Evidence (STRIDE), assess the quality of the data, clean the data, use the data to generate city-specific price and purity series, and build national indexes of price and purity from city-specific estimates. For anyone interested in replicating the results presented in the main report, this technical report serves as a roadmap. In addition, it provides a justification for the decisions made throughout the development of the main report. The report is divided into seven main sections: (1) acquiring the data and constructing the sample and defining key variables from the data; (2) redefining distribution levels for specific illicit drugs; (3) establishing methodological changes for the price and purity econometric models and developing the model specifications for price or purity of each distribution level for each drug; (4) empirical results for both purity and price equation; (5) constructing the national price and purity indexes; (6) accounting for uncertainty, based on numerous assumptions that are not known with certainty; and (7) supplemental analyses to test the reasonableness of assumptions made throughout the modeling process, specifically an investigation of heroin (salt-undetermined series) and the influence of observations from the Washington, DC, Metropolitan Police force. Appendixes A-H, tables and figures