THE SHORT- AND LONG-RANGE EFFECTS OF A LANGUAGE STIMULATION PROGRAM ON THE LINGUISTIC ABILITY AND INTELLIGENCE OF EDUCATIONALLY DISADVANTAGED FIRST-GRADE NEGRO CHILDREN WERE STUDIED. SUBJECTS WERE RANDOMLY PLACED IN EXPERIMENTS (E) AND CONTROL (C) GROUPS OF 32 PUPILS MATCHED ON STANDARDIZED PRETEST BATTERIES WHICH DETERMINED THEIR LANGUAGE AND MENTAL AGES. THEY ALSO WERE MATCHED BY SEX AND SOCIAL CLASS. THE E-GROUP RECEIVED THE FIRST 40 LESSONS IN THE EXPERIMENTAL EDITION OF THE PEABODY LANGUAGE DEVELOPMENT KIT WHEREAS THE C-GROUP HAD NO SPECIAL TREATMENT BUT ONLY PARTICIPATED IN THE TESTING PROGRAM. IMMEDIATE POSTTESTING WITH THE PRETEST EVALUATION BATTERY SHOWED "VERY" SIGNIFICANT GAINS BY THE E-GROUP IN IQ, MENTAL AGE, AND LANGUAGE AGE, BUT NO DIFFERENCE IN READING ABILITY, EXCEPT THAT GIRLS CONSISTENTLY SCORED HIGHER THAN BOYS. WHEN THE SUBJECTS WERE RE-EVALUATED 20 MONTHS AFTER THE END OF TREATMENT, THE E-GROUP HAD MAINTAINED ITS GAINS IN LANGUAGE, MENTAL AGE, AND IQ, ALTHOUGH THE ABSOLUTE DIFFERENCE BETWEEN GROUPS DIMINISHED SOMEWHAT ON LANGUAGE AGE SCORES. ON THIS LATER EVALUATION THE E-GROUP ALSO SCORED SIGNIFICANTLY HIGHER ON TWO STANDARD READING TESTS. THE FINDINGS IMPLY THAT THE CUMULATIVE DEFECT IS FOUND AMOUNG DEPRIVED CHILDREN IS NOT IMMUTABLE AND THAT EARLY STIMULATION PROGRAMS CAN REVERSE THE DOWNWARD TRENDS IN THEIR LANGUAGE AND MENTAL ABILITIES. STUDIES OF THE MOST POTENTIALLY SUCCESSFUL PRACTICES FOR SUCH A PROGRAM AND OF ITS APPLICABILITY TO OTHER GROUPS ARE NEEDED. (NH)