  The balance function is a new observable based on the principle that charge
is locally conserved when particles are pair produced. Balance functions have
been measured for charged particle pairs and identified charged pion pairs in
Au+Au collisions at $\sqrt{s_{NN}}$ = 130 GeV at the Relativistic Heavy Ion
Collider using STAR. Balance functions for peripheral collisions have widths
consistent with model predictions based on a superposition of nucleon-nucleon
scattering. Widths in central collisions are smaller, consistent with trends
predicted by models incorporating late hadronization.
