We present high resolution imaging of the nucleus of NGC4258 from 1 \micron to 18 \micron .
Our observations reveal that the previously discovered compact source of emission is unresolved even at the near-infrared resolution of \sim 0.2 \arcsec FWHM which corresponds to about 7 pc at the distance of the galaxy .
This is consistent with the source of emission being the region in the neighborhood of the purported 3.5 \times 10 ^ { 7 } M _ { \sun } black hole .
After correcting for about 18 mags of visual extinction , the infrared data are consistent with a F _ { \nu } \propto \nu ^ { -1.4 \pm 0.1 } spectrum from 1.1 \micron to 18 \micron , implying a non-thermal origin .
Based on this spectrum , the total extinction corrected infrared luminosity ( 1 - 20 \micron ) of the central source is 2 \times 10 ^ { 8 } L _ { \sun } .
We argue that the infrared spectrum and luminosity of the central source obviates the need for a substantial contribution from a standard , thin accretion disk at these wavelengths and calculate the accretion rate through an advection dominated accretion flow to be \dot { M } \sim 10 ^ { -3 } M _ { \sun } /yr .
The agreement between these observations and the theoretical spectral energy distribution for advection dominated flows provides evidence for the existence of an advection dominated flow in this low luminosity AGN .