  We present experimental results demonstrating controllable dispersion in a
ring laser by monitoring the lasing-frequency response to cavity-length
variations. Pumping on an N-type level configuration in ${}^{87}$Rb, we tailor
the intra-cavity dispersion slope by varying experimental parameters such as
pump-laser frequency, atomic density, and pump power. As a result, we can tune
the pulling factor (PF), i.e. the ratio of the laser frequency shift to the
empty cavity frequency shift, of our laser by more than an order of magnitude.
