  We tune the dimensionality of pancake-shaped strongly-interacting $^6$Li
Fermi gas clouds from two-dimensional (2D) to quasi-2D, by controlling the
ratio of the radial Fermi energy $E_F$ to the harmonic oscillator energy
$h\nu_z$ in the tightly confined direction. In the 2D regime, where
$E_F<<h\nu_z$, the measured radio frequency resonance spectra are in agreement
with 2D-BCS theory. In the quasi-2D regime, where $E_F\simeq h\nu_z$, the
measured spectra deviate significantly from 2D-BCS theory. For both regimes,
the measured cloud radii disagree with 2D-BCS mean field theory, but agree
approximately with predictions using a free energy derived from the
Bethe-Goldstone equation.
