We describe recent applications of circular dichroism (CD) spectroscopy to develop simple methods for the study of supramolecular functional materials. Examples include the development of a CD method to identify supramolecules in action (and to determine Hill coefficients for exergonic self-assembly), or CD methods to measure osmotic pressure and the activity of ion channels and pores. For the latter two applications, G-quartets are introduced as versatile functional CD probes in chirogenic vesicles.