  The same light-front wave functions of the proton are involved in both the
anomalous magnetic moment of the nucleon and the Sivers function. Using the
diquark model, we derive a simple relation between the anomalous magnetic
moment and the Sivers function, which should hold in general with good
approximation. This relation can be used to provide constraints on the Sivers
single spin asymmetries from the data on anomalous magnetic moments. Moreover,
the relation can be viewed as a direct connection between the quark orbital
angular momentum and the Sivers function.
