How could quantum mechanics possibly be important in biology We will discuss this question in the light of recent experiments that suggest that quantum mechanics - or at least coherence - is at play after photosynthesis is initiated by light. First, we give a brief description of light harvesting in photosynthesis. We follow this with an introduction to two-dimensional electronic spectroscopy, in which we demonstrate how this spectroscopic technique can be used to indicate coherent contributions to energy transfer dynamics. As a final point, we focus on the possible role that coherence may play in photosynthetic biological systems. © 2013 The Author(s) 2013. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. All rights reserved. For Permissions, please e-mail: firstname.lastname@example.org.