THREE HEAD START PROGRAMS WERE ESTABLISHED TO INVESTIGATE THE DIFFERENCES BETWEEN FOUR GROUPS OF CHILDREN IN THE AREAS OF INTELLIGENCE, COGNITION AND ACHIEVEMENT, ENVIRONMENT, AND PARENTAL EXPECTATIONS. THE FOUR GROUPS WERE (1) THE SR GROUP IN WHICH THE CHILDRENS' PARENTS SOUGHT OUT ENTRY FOR THEIR CHILDREN IN THE HEAD START PROGRAM, (2) THE SAP GROUP IN WHICH THE CHILDREN'S ENTRY INTO THE PROGRAM WAS SOUGHT OUT BY THE HEAD START PERSONNEL, (3) THE SANP GROUP WHO WERE LIKEWISE SOUGHT OUT BY PROGRAM PERSONNEL BUT DID NOT PARTICIPATE, AND (4) THE MC GROUP WHO WERE NON-PARTICIPATING MIDDLE CLASS CHILDREN AVERAGING A YEAR YOUNGER IN AGE THAN THE OTHER THREE GROUPS. GROUPS 1 AND 2 PARTICIPATED IN THE HEAD START PROGRAM ONLY. GROUP 1, 2, AND 3 WERE CHILDREN OF LOWER-INCOME FAMILIES. THE HEAD START PROGRAM LASTED SIX MONTHS. TESTING WAS CARRIED ON IN ALL FOUR GROUPS. ONE BATTERY OF TESTS WAS GIVEN ALL CHILDREN NEAR THE TIME GROUPS 1 AND 2 BEGAN THE PROGRAM. GROUPS 1 AND 2 WERE GIVEN THE BATTERY AGAIN AT THE CONCLUSION OF THE PROGRAM. THE RESULTS SHOWED THAT THE MC GROUP SCORED CONSISTENTLY HIGHEST ON ALL TESTS. THE SR GROUP WAS GENERALLY SECOND HIGHEST. THE ENVIRONMENT OF GROUPS 1 AND 4 APPEARED MORE FAVORABLE TO A STIMULATION OF EFFECTIVE LEARNING THAN THE VERY DEPRIVED ENVIRONMENTS OF GROUPS 2 AND 3. ALSO, THE PARENTS OF GROUP 1 AND 4 CHILDREN APPEARED MORE ENCOURAGING TOWARD AND INTERESTED IN THEIR CHILD'S DEVELOPMENT. (WD)