We critically examine the basic paradigm for the origin of the 2-3 hr perio
d gap in cataclysmic variables (CVs), i.e., binary systems in which a white
dwarf accretes from a relatively unevolved, low-mass donor star. The obser
ved orbital period distribution for similar to 300 CVs shows that these sys
tems typically have orbital periods, P-orb, in the range of similar to 80 m
inutes to similar to8 hr but a distinct dearth of systems with 2 less than
or similar to P-orb(hr) less than or similar to 3. This latter feature of t
he period distribution is often referred to as the "period gap." The conven
tional explanation for the period gap involves a thermal bloating of the do
nor star for P-orb greater than or similar to 3 hr due to mass transfer rat
es that are enhanced over those that could be driven by gravitational radia
tion (GR) losses alone (e.g., magnetic braking). If for some reason the sup
plemental angular momentum losses become substantially reduced when P-orb d
ecreases below similar to3 hr, the donor star will relax thermally and shri
nk inside of its Roche lobe. This leads to a cessation of mass transfer unt
il GR losses can bring the system into Roche lobe contact again at P-orb si
milar to 2 hr. We carry out an extensive population synthesis study of CVs,
starting from similar to3 x 10(6) primordial binaries and evolving some si
milar to2 x 10(4) surviving systems through their CV phase. In particular w
e study current-epoch distributions of CVs in the (M)over dot-P-orb, R-2-P-
orb, M-2-P-orb, q-P-orb, T-eff-P-orb, and L-2-P-orb planes, where is (M)ove
r dot the mass transfer rate, q is the mass ratio M-2/M-1, and M-2, R-2, T-
eff, and L-2 are the donor star mass, radius, effective temperature, and lu
minosity, respectively. This work presents a new perspective on theoretical
studies of the long-term evolution of CVs. In particular, we show that if
the current paradigm is correct, the secondary masses in CVs just above the
period gap should be as much as similar to 50% lower than would be inferre
d if one assumes a main-sequence radius-mass relation for the donor star. W
e quantify the M-2-P-orb relations expected from models wherein the donor s
tars are thermally bloated. Finally, we propose specific observations, invo
lving the determination of secondary masses in CVs, that would allow for a
definitive test of the currently accepted model (i.e., interrupted thermal
bloating) for the period gap in CVs.