  We incorporate nonlinear covers of quasisplit reductive groups into the
Langlands program, defining an L-group associated to such a cover. This L-group
is an extension of the absolute Galois group of a local or global field $F$ by
a complex reductive group. The L-group depends on an extension of a quasisplit
reductive $F$-group by $\mathbf{K}_2$, a positive integer $n$ (the degree of
the cover), an injective character $\epsilon \colon \mu_n \rightarrow {\mathbb
C}^\times$, and a separable closure of $F$. Our L-group is consistent with
previous work on covering groups, and its construction is contravariantly
functorial for certain well-aligned homomorphisms. An appendix surveys torsors
and gerbes on the \'etale site, as they are used in a crucial step in the
construction.
