  We perform shell model calculations using a quadrupole-quadrupole interaction
(Q.Q) in single a j shell space. We show that this one-parameter interaction is
a good predictor of where nuclear isomerism occurs and where it does not occur.
The limitations of this interaction are also discussed. We then include other
interactions e.g. in the f_{7/2} shell those obtained from the (local) spectrum
of a 2 particle system and then from a 2 hole system. In the g_{9/2}where there
is insufficient empirical data from the 2 hole system and so various empirical
interactions are used.
