DATA WERE OBTAINED FOR EACH INMATE FROM HIS PRISON FILE. NEARLY HALF OF THE INMATES IN MT. EDEN ON THE DAY OF THE SURVEY HAD AN ALIAS NOTED ON THEIR FILE, BUT 65 PER CENT EITHER HAD NO ALIAS OR AN ALIAS WHICH APPEARED TO STEM FROM AN ADMINISTRATIVE MISTAKE RATHER THAN A DELIBERATE CHANGE OF NAME. OLDER INMATES AND MEMBERS OF NATIVE MINORITIES WERE MORE LIKELY TO HAVE AN ALIAS. FIRST OFFENDERS AND INMATES WHO HAD ATTENDED SECONDARY SCHOOL WERE LESS INCLINED TO HAVE AN ALIAS. THERE WAS NO STRONG AND CONSISTENT RELATIONSHIP BETWEEN MOST RECENT OFFENSE AND ALIAS USE. A STEPWISE DISCRIMINANT ANALYSIS INVOLVING THE VARIABLES OF AGE, EDUCATION, NUMBER OF PREVIOUS OFFENSES, AND LENGTH OF CURRENT SENTENCE SUCCESSFULLY CLASSIFIED 63.36 PER CENT OF THE INMATES INTO 'NO ALIAS' AND 'ALIAS' GROUPS. IN GENERAL, THE DATA SHOWED THAT PRISON INMATES ARE LIKELY TO USE AN ALIAS AND THAT ALIAS USE IS ASSOCIATED WITH INCREASING LEVELS OF CRIMINALITY, AND ALSO WITH ETHNIC ORIGIN, AGE, AND EDUCATION. (AUTHOR ABSTRACT)...ELW