We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ($K^+ \rightarrow ��^+ ��_��$) at the NuMI beamline absorber. These signal $��_��$-carbon events are distinguished from primarily pion decay in flight $��_��$ and $\overline��_��$ backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9$��$ level. The muon kinetic energy, neutrino-nucleus energy transfer ($��=E_��-E_��$), and total cross section for these events is extracted. This result is the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of $��$ using neutrinos, a quantity thus far only accessible through electron scattering.

6 pages, 4 figures