  Spatial extension is an important characteristic for correctly associating
gamma-ray-emitting sources with their counterparts at other wavelengths and for
obtaining an unbiased model of their spectra. We present a new method for
quantifying the spatial extension of sources detected by the Large Area
Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space
Telescope (Fermi). We perform a series of Monte Carlo simulations to validate
this tool and calculate the LAT threshold for detecting the spatial extension
of sources. We then test all sources in the second Fermi-LAT catalog (2FGL) for
extension. We report the detection of seven new spatially extended sources.
