RHIC Results on J/Psi

Quarkonia ($J/\psi$, $\psi$', $\Upsilon$) production provides a sensitive probe of gluon distributions and their modification in nuclei; and is a leading probe of the hot-dense (deconfined) matter created in high-energy collisions of heavy ions. We will discuss the current understanding of the production process and of the cold-nuclear-matter effects that modify this production in nuclei in the context of recent p+p and p(d)+A quarkonia measurements. Then we will review the latest results for nucleus-nucleus collisions from RHIC, and together with the baseline results from d+A and p+p collisions, discuss several alternative explanations for the observed suppressions and future prospects for distinguishing these different pictures.