  We present the results of a 2-epoch variability survey in the Hubble Deep
Field with the goal of investigating the population of AGN to z=1. The primary
data sets analyzed for galactic variability are the original HDF observations
obtained in 1995 and a second V-band image obtained 5 years later in 2000. We
find evidence for nuclear variability in 16 of 217 galaxies brighter than
V_nuc=27.5. Correcting for incompleteness and spurious detections, variable
nuclei make up ~8% of the surveyed galaxies. Seven of our variable sources are
coincident with X-ray sources detected in the 2Ms Chandra survey. We find that
44% of the variable nuclei are associated with mid-IR detections at 15 microns
and 31% are detected at 1.4GHz. Optical spectra are available for 13 of the 16
variables. One is a broad-line AGN and 2 others show weak evidence of type 2
AGNs. With the assumption that these variables are all active nuclei, we
estimate the AGN LF at 0.4<z<1.1 extending to M_B=-15. We find evidence for an
increase in the number density of faint AGN when comparing to the local Seyfert
luminosity function. The LF for optically varying nuclei appears to rise in
number density with no evidence of turning over at these faint magnitudes.
