Methodological naturalism arises as a topic in metaethics in two ways. One is the issue of whether we should be methodological naturalists when doing our moral theorising, and another is whether we should take a naturalistic approach to metaethics itself. Interestingly, these can come apart, and some naturalist programs in metaethics justify a non-scientific approach to our moral theorising. This paper discusses the range of approaches that fall under the general umbrella of methodological naturalism, and how naturalists view the role of science in ethics and metaethics. It discusses how naturalism interacts with the use of intuitions, using conceptual analysis, and reflective equilibrium methods. Finally, it discusses some ways using scientific investigation can make distinctive contributions to ethics and metaethics.