The effect of schooling, word structure and age on the phonemic awareness was tested by the use of words categories, which the number of syllables was the determining factor in terms of difficulty. The main hypothesis was that the development of phonemic awareness depended of the children's age, schooling and word's structure. The independent variables that were taken into consideration were the age, school and difficulty in the word's structure. The experimenter based on two pilot studies concluded in the test format. The sample that used in the test format constituted of 40 children of 63 to 102 months old which 20 of them were kindergarten children and 20 were students at the first class of an elementary school at Athens, Greece. The data analysis revealed that all of the original hypotheses were supported, because statistical significant was found. Therefore it was proved that the schooling, children's age and word's structure have affection in the development of phonemic awareness.