Grounding is necessary just in case: if P grounds Q, then necessarily: if P, then Q. Many accept this principle. Others propose counterexamples. Instead of straightforwardly arguing for, or against, necessity, I explain the sense in which grounding is necessary and contingent. I argue that there are two kinds of grounding: what-grounding (which tells us what it is for things to be the case) and why-grounding (which tells us why things are the case), where the former kind is necessary while the latter is contingent.
