In the Learning Research and Development Center (LRDC) Beginning Reading Program, vowels are color-coded so that different spellings, representing a single vowel sound, maintain some feature in common. Such color-coding imposes a structure which effectively reduces the uncertainty in associating visually different stimuli with a similar oral response. The program consists of two sets of twelve children's books with color-coding used systematically through Book 8 or 11. Words are color-coded according to rules applying to each set of two stories that follow the introduction of a new phoneme-to-grapheme association, with the amount of color prompting reduced in the alternate set of readers. In the second story of the first set of readers, only words which have not previously appeared at least five times in color in prior stories are color-coded. In the alternate set of readers, only words which have never appeared before in prior stories are color-coded. During 1969-70 several studies were made to determine the effectiveness of color-coding: a testing program to prove pupil achievement, a study to investigate the question of how much color prompting benefits the pupils, and a test to determine how well individual elements were learned by the same children. (HS)