  I present a study of the high-energy gamma-ray properties of the flat
spectrum radio quasar, PKS 1510-089, based on 3.75 years of observations with
the Large Area Telescope (LAT) detector on-board the Fermi gamma-ray Space
Telescope. Throughout the observing period, the 0.1 GeV < E < 300 GeV gamma-ray
flux was highly variable, undergoing several flaring events where the daily
flux exceeded 10^{-5} photons cm^{-2} s^{-1} on 3 separate occasions. The
increased photon statistics of these large flares allowed the observations to
be re-analysed in 6 and 3 hour intervals, revealing flux doubling timescales as
small as 1.3\pm0.12 hours during the flare rise time, and flux halving
timescales of 1.21\pm0.15 hours during the flare decay. These are the smallest
variability timescales measured to date at MeV-GeV energies for the Flat
Spectrum Radio Quasar class of Active Galactic Nuclei.
  The >10^{-5} photons cm^{-2} s^{-1} flare events were also studied in more
detail in an attempt to uncover evidence for the location of PKS 1510-089's
gamma-ray emission region. In particular, two approaches were used: (i)
searching for an energy dependence to the cooling timescales, and (ii)
searching for evidence of a spectral cut-off. Furthermore, an analysis of the
highest photon events within the 3.75 year data set finds PKS 1510-089 to be a
source of >20 GeV gamma-rays at the 13.5\sigma confidence level; a
observational property which is difficult to explain in the traditional view
that gamma-ray emission from Active Galactic Nuclei originates from the base of
the relativistic jet.
  The combined results of these two approaches, along with the confirmation of
>20 GeV photon flux from PKS 1510-089, suggest the presence of multiple
gamma-ray emission regions being located in both the broad line region and
molecular torus region of PKS 1510-089.
