Cross-frequency coupling is a rich signal marker of basic physiological mechanisms of neural population activity and interactions. It has been proposed to serve a functional role in neuronal computation,  communication, and learning, and has been shown to correlate with brain function and dysfunction. Recently, a considerable amount of work has focused on phase-amplitude coupling (PAC)– a form of cross-frequency coupling where the phase of lower rhythm determines the amplitude of faster rhythmic bursts. PAC assessment methods currently in use have some limitations including their sensitivity to noise, the requirement for the user to define certain parameters, and the lack of data-driven estimation of frequency for phase. Here, we propose a new measure called amplitude-phase coupling (APC) for assessing PAC that can address these issues. The APC also provides a measure of the coupling strength, and preferred phase, and can be extended to consider different modes of coupling. The proposed technique is first evaluated for simulated data and then applied to actual hippocampal recordings obtained from freely moving rats.