Harmonic expectation and surprise have been extensively studied in the context of Western art music. A resulting body of evidence suggests that these are important factors in listeners’ musical experience and enjoyment. In addition, centuries of Western art music theory have resulted in an in-depth understanding of the musical techniques used by common practice composers to evoke expectation and surprise. This thesis expands on this knowledge by investigating harmonic expectation and surprise within jazz and popular music. These styles have been neglected in the research due to an assumption that the common practice stimuli typically used in harmonic expectation experiments are representative of all Western tonal styles. However, due to the influence of blues and other factors, there are differences in tonal frameworks, narrative structures, harmonic languages, and chord functions in contemporary styles. Therefore, techniques to elicit surprise within common practice music may not have the same effect in jazz and popular music. Results of this investigation suggest that common practice is not paradigmatic of jazz and popular music with respect to expectation and surprise. Techniques associated with surprise in common practice music, such as the traditional deceptive cadence to VIm, were found to be significantly weakened within jazz and popular music contexts, where surprise was found to be primarily elicited through chromatic techniques such as modal interchange. Results revealed a linear relationship between surprise and preference for pop and rock musicians, and an inverted-U relationship for jazz musicians. Pop music was found to elicit greater use of sensory processing strategies in listeners, in comparison to jazz. These findings reinforce arguments that the tonal systems of common practice, jazz and popular music are distinct and unique. They provide the first comprehensive account of the musical techniques that elicit surprise in contemporary styles and establish an important initial link between music cognition and applied music theory. The results may be of note for those advocating for increased musical diversity and improvisation in the fields of musicology, music education, and music cognition.