  Determining the precise ages of young (tens to a few hundred Myr) kinematic
(``moving") groups is important for placing star, protoplanetary disk, and
planet observations on an evolutionary timeline. The nearby $\sim$25 Myr-old
$\beta$ Pictoris Moving Group (BPMG) is an important benchmark for studying
stars and planetary systems at the end of the primordial disk phase. Gaia DR3
astrometry and photometry, combined with ground-based observations and more
sophisticated stellar models, permit a systematic re-evaluation of BPMG
membership and age. We combined Gaia astrometry with previously published
radial velocities to evaluate moving group membership in a Bayesian framework.
To minimize the effect of unresolved stellar multiplicity on age estimates, we
identified and excluded multi-star systems using Gaia astrometry, ground-based
adaptive optics imaging, and multi-epoch radial velocities, as well as
literature identifications. We estimated age using isochrone and
lithium-depletion-boundary fitting with models that account for the effect of
magnetic activity and spots on young, rapidly rotating stars. We find that age
estimates are highly model-dependent; Dartmouth magnetic models with ages of
23$\pm$8 Myr and 33$^{+9}_{-11}$ Myr provide best fits to the lithium depletion
boundary and Gaia $M_G$ vs. $B_{P}$-$R_{P}$ color-magnitude diagram,
respectively, whereas a Dartmouth standard model with an age of 11$^{+4}_{-3}$
Myr provides a best fit to the 2MASS-Gaia $M_{K_S}$ vs. $B_{P}$-$R_{P}$
color-magnitude diagram.
