THE FIRST OF A SERIES OF STUDIES DESIGNED TO INVESTIGATE THE SUITABILITY OF INSTRUCTIONAL MATERIALS WITH REGARD TO LEVELS OF DIFFICULTY IS REPORTED. THE STUDY ATTEMPTED TO DETERMINE WHETHER SOME RANGE OF DIFFICULTY MAXIMIZED THE AMOUNT OF INFORMATION STUDENTS GAIN AS A CONSEQUENCE OF READING INSTRUCTIONAL MATERIALS. IN ORDER TO FORM 129 PAIRS ACCORDING TO READING ABILITY, STUDENTS RANGING FROM GRADE 3 THROUGH GRADUATE LEVEL WERE GIVEN A CLOZE TEST. ONE MEMBER OF EACH PAIR WAS GIVEN A CLOZE READABILITY TEST OVER A PASSAGE TO DETERMINE THE DIFFICULTY OF THE PASSAGE FOR THAT PAIR. THE OTHER MEMBER OF THE PAIR DETERMINED HOW MUCH INFORMATION THAT PAIR GAINED BY READING THE PASSAGE. HE FIRST GUESSED THE ANSWERS TO A MULTIPLE CHOICE TEST AND THEN READ THE PASSAGE AND TOOK THE SAME TEST AGAIN. INFORMATION GAIN WAS DETERMINED BY SUBTRACTING THE SCORE OF HIS FIRST TEST FROM THE SCORE OF THE SECOND. IT APPEARED FROM THE DATA OBTAINED THAT IT MAY BE POSSIBLE TO ESTABLISH FAIRLY DEFINITE STANDARDS OF WHAT IS A SUITABLE PASSAGE FOR USE BY A CHILD. IT WAS FOUND THAT SCORES ON CLOZE TESTS DO NOT DEPEND SOLELY ON A SUBJECT'S PRIOR KNOWLEDGE OF THE CONTENT OF A PASSAGE. EIGHT REFERENCES ARE GIVEN. THIS PAPER WAS PRESENTED AT THE INTERNATIONAL READING ASSOCIATION CONFERENCE (BOSTON, APRIL 24-27, 1968). (KJ)