  We analyse the baryon magnetic moments in a model that relates them to the
parton spins $\Delta u$, $\Delta d$, $\Delta s$, and includes a contribution
from orbital angular momentum. The specific assumption is the existence of a
3-quark correlation (such as a flux string) that rotates with angular momentum
$\langle L_z \rangle$ around the proton spin axis. A fit to the baryon magnetic
moments, constrained by the measured values of the axial vector coupling
constants $a^{(3)}=F+D$, $a^{(8)}=3F-D$, yields $\langle S_z \rangle = 0.08 \pm
0.13$, $\langle L_z \rangle = 0.39 \pm 0.09$, where the error is a theoretical
estimate. A second fit, under slightly different assumptions, gives $\langle
L_z \rangle = 0.37 \pm 0.09$, with no constraint on $\langle S_z \rangle$. The
model provides a consistent description of axial vector couplings, magnetic
moments and the quark polarization $\langle S_z \rangle$ measured in deep
inelastic scattering. The fits suggest that a significant part of the angular
momentum of the proton may reside in a collective rotation of the constituent
quarks.
