BASAL READER SYSTEMS FOR BEGINNERS WERE ANALYZED TO DETERMINE THE EFFECTS OF SPECIFIC SYSTEM FEATURES ON THE READING ACHIEVEMENT OF FIRST-GRADE CHILDREN OF DIFFERENT SEX AND LEVELS OF INTELLIGENCE. THE PROJECT COVERED THE FOLLOWING SYSTEMS--(1) THE LIPPINCOTT "BASIC READING" SERIES, (2) THE "EARLY-TO-READ INITIAL-TEACHING-ALPHABET" PROGRAM, AND (3) THE SCOTT-FORESMAN "NEW BASIC READERS" SERIES. APPROXIMATELY 650 CHILDREN IN 26 FIRST-GRADE CLASSES WERE INCLUDED IN THE EXPERIMENTAL SAMPLE. THE INTERACTIONAL EFFECTS OF THE THREE EXPERIMENTAL TREATMENTS, THE THREE LEVELS OF INTELLIGENCE, AND THE TWO SEXES WERE ANALYZED. THE LIPPINCOTT AND "EARLY-TO-READ" PROGRAMS UTILIZED AN APPROACH TO READING THAT IS CONSIDERABLY MORE ANALYTIC THAN THE SCOTT-FORESMAN PROGRAM. STUDENTS USING THE LIPPINCOTT SERIES EXPERIENCED SIGNIFICANTLY HIGHER ACHIEVEMENT ON THE SUBTESTS OF VOCABULARY AND SPELLING IN THE "STANFORD ACHIEVEMENT TEST" THAN THE OTHER TWO GROUPS. AMONG ANY OF THE THREE BASAL READER SYSTEMS, THE FACTOR OF SEX DID NOT PRODUCE DIFFERENTIAL RESULTS. INTELLIGENCE WAS NOT A MAJOR FACTOR IN DISTINGUISHING PROBABLE CHANGES FOR SUCCESS. ON THE VARIABLES OF POSTINSTRUCTION ORAL READING AND WORD RECOGNITION, THE LIPPINCOTT AND "EARLY-TO-READ" STUDENTS WERE COMPARABLE WHEN MEASURED. BOTH GROUPS WERE SIGNIFICANTLY SUPERIOR TO THE SCOTT-FORESMAN PUPILS ON THESE SPECIFIC VARIABLES. (JH)