This research report examines the pronunciation that children give to synthetic words containing vowel-cluster spellings and analyzes the observed pronunciations in relation to common English words containing the same vowel clusters. The pronunciations associated with vowel-cluster spellings are among the most unpredictable letter-sound correspondences in English. More than 425 elementary school pupils in Wisconsin schools were administered a 100-item, multiple-choice test of 90 synthetic words containing vowel clusters ("ai,""au,""ay,""ea,""ie,""oa," and "ow") and 10 additional check items. Results and conclusions discuss the relationship of vowel cluster pronunciation, grade level, sex, reading level, community type (suburban, urban, and rural), and response type. Inclusion of extensive statistical data supports the research findings. Appendixes contain: (1) the International Phonetic Alphabet symbols for American English; (2) vowel-cluster, multiple-choice tests; (3) subject data; (4) summary of tests administered; and (5) F values of main effects and interactions for analyses 1 and 2. A bibliography is provided. (RL)