THE COMPARATIVE VALIDITY OF THE LEE-CLARK READING READINESS TEST AND THE CALIFORNIA TEST OF MENTAL MATURITY (CTMM) FOR PREDICTING GRADE 1 READING SUCCESS WAS STUDIED. ALL ENTERING FIRST-GRADE PUPILS IN TWO ELEMENTARY SCHOOLS IN A LOW-MIDDLE-CLASS COMMUNITY WERE ADMINISTERED BOTH TESTS DURING THE FIRST 3 WEEKS OF SCHOOL. PERFORMANCES ON THESE TESTS WERE CORRELATED WITH SCORES ON THE LEE-CLARK READING TEST, PRIMER (FORM A), AND TEACHER MARKS NEAR THE END OF THE SCHOOL YEAR. THE READINESS TEST DID AT LEAST AS WELL IN PREDICTING FIRST-GRADE PERFORMANCE AS THE CTMM. THIS FINDING IS CONSISTENT WITH OTHER INVESTIGATIONS WHICH HAVE COMPARED READINESS TESTS WITH INTELLIGENCE TESTS FOR PREDICTING GRADE 1 READING SUCCESS. A TABLE AND REFERENCES ARE INCLUDED. THIS PAPER WAS PRESENTED AT THE AMERICAN EDUCATIONAL RESEARCH ASSOCIATION MEETING (NEW YORK CITY, FEBRUARY 1967). (H)