Guidance of axons to their targets in the developing nervous system requires a myriad of downstream signaling molecules to coordinate growth cone movement. One of the most important of these is calcium, and over the past few years many new insights have been gained into the role of calcium in axon guidance. In this review we focus on mechanisms of calcium entry into the growth cone and its downstream effects on both growth cone motility and turning. We particularly highlight the role of calcium concentrations in determining attractive versus repulsive responses to graded guidance cues, and their role in guidance by the morphogen Wnt5a.