Much recent work on language and cognition has examined the psychological status of collocations/formulas/multi-word expressions as mentally stored units. These studies have used a variety of statistical metrics to quantify the degree of strength or association of these sequences, and then they have correlated these strengths with particular behavioral effects that evidence mental storage. However, the relationship between intonational prosody and storage of collocations has received little attention. Through a corpus-based approach, this study examines the hypothesis that boundaries between successive intonation units avoid splitting word bigrams that exhibit high statistical association, with such high association taken to be an index of mental storage of these bigrams. Conversely, bigrams exhibiting lower statistical association ought to be more likely to be split by intonation unit boundaries under this hypothesis.