  We present measurements of the polarization of the $ J/\psi $ produced in
800-GeV proton interactions with a copper target. Polarization of the $ J/\psi
$ is sensitive to the $ c \bar{c} $ production and hadronization processes. A
longitudinal polarization is observed at large $ x_{F} $, while at small $
x_{F} $ the state is produced essentially unpolarized or slightly transversely
polarized. No significant variation of the polarization is observed versus $
p_{T} $.
