  We present the results of a study of differential rotation on the K2 IV
primary of the RS CVn binary II Pegasi (HD 224085) performed by inverting light
curves to produce images of the dark starspots on its surface. The data were
obtained in the standard Johnson B and V filter passbands via the Tennessee
State University T3 0.4-m Automated Photometric Telescope from JD 2447115.8086
to 2454136.6221 (1987 November 16 to 2007 February 5). The observations were
subdivided into 68 data sets consisting of pairs of B and V light curves, which
were then inverted using a constrained non-linear inversion algorithm that
makes no a priori assumptions regarding the number of spots or their shapes.
The resulting surface images were then assigned to 21 groups corresponding to
time intervals over which we could observe the evolution of a given group of
spots (except for three groups consisting of single data sets). Of these 21
groups, six showed convincing evidence of differential rotation over time
intervals of several months. For the others, the spot configuration was such
that differential rotation was neither exhibited nor contraindicated. The
differential rotation we infer is in the same sense as that on the Sun: lower
latitudes have shorter rotation periods. From plots of the range in longitude
spanned by the spotted regions vs. time, we obtain estimates of the
differential rotation coefficient k defined in earlier work by Henry et al.,
and show that our results for its value are consistent with the value obtained
therein.
