Three treatment technologies for removing arsenic from groundwater in Albuquerque, New Mexico, were compared: ion exchange (IX), iron hydroxide coagulation followed by microfiltration (C/MF), and activated alumina (AA) adsorption. Foran 8,700-m3/d (2.3-mgd) arsenic treatment facility, capital costs of the three processes were similar: $5.2 million, $4.1 million, and $4.6 million, respectively. Annual operations and maintenance costs were $447,000, $273,000 and $444,000, respectively. The principal differences were the result of large salt requirements for the IX process and the need to reduce the pH to 6 for AA adsorption, followed by base addition to stabilize the water. The C/MF system was selected for a demonstration facility in Albuquerque. Includes 11 references, tables, figures.