  We review recent advances in our understanding of magnetism in the solar
nebular and protoplanetary disks (PPDs). We discuss the implications of theory,
meteorite measurements, and astronomical observations for planetary formation
and nebular evolution. Paleomagnetic measurements indicate the presence of
fields of 0.54$\pm$0.21 G at $\sim$1 to 3 astronomical units (AU) from the Sun
and $\gtrsim$0.06 G at 3 to 7 AU until >1.22 and >2.51 million years (Ma) after
solar system formation, respectively. These intensities are consistent with
those predicted to enable typical astronomically-observed protostellar
accretion rates of $\sim$10$^{-8}$ M$_\odot$ yr$^{-1}$, suggesting that
magnetism played a central role in mass and angular momentum transport in PPDs.
Paleomagnetic studies also indicate fields <0.006 G and <0.003 G in the inner
and outer solar system by 3.94 and 4.89 Ma, respectively, consistent with the
nebular gas having dispersed by this time. This is similar to the observed
lifetimes of extrasolar protoplanetary disks.
