A study addressed the relationship of culturally related schema to comprehension and examined the effect of instruction using thematic units upon the development of background knowledge. Subjects were 25 pupils (aged 8 to 10 years) enrolled in a primary school in Scotland and 21 students enrolled in a 3rd-grade class in Texas. Subjects listened to a passage about their own culture and responded to a 10-item multiple choice test. The subjects then listened to a passage about the other culture and were given a similar test. The subjects participated in a one-week thematic unit about the other culture and again answered the culturally specific questions. Results indicated that not all subjects in a cultural group shared the same knowledge or understanding of their own culture, and that subjects of a culture knew considerably more about other cultures than was expected. Results also indicated that the use of thematic units as a method for improving comprehension was a viable strategy provided that certain factors were considered, e.g.: (1) the content taught; (2) the strategies planned; and, most importantly, (3) the characteristics of the students instructed. (Six tables of data and 2 figures displaying the specific vocabulary and concepts in the stories read to the subjects are included; 22 references are attached.) (RS)