Pyridones such as 1 undergo [4+4] photodimerization, with high head-to-tail regioselectivity and moderate regioselectivity for the trans isomer 2. We have studied the case of N-benzyl pyridone 1 in methanol, where the product 2 crystallizes from solution as it forms, using only the sun as the light source. The effect of concentration, time and flask size on the yield of 2 was determined. This is the first example of pyridone dimerization using only sunlight.