The large coherence length of conventional superconductors causes the
critical region near Tc to be unobservably small, leading to the impre
ssion that mean-field theory can adequately explain properties near th
e transition. The high-temperature superconductors, however, have such
strongly type-II character that the critical, or at least an intermed
iate critical, region is experimentally accessible. We demonstrate the
applicability of XY-like critical scaling to magnetization, heat capa
city and conductivity data and through the fitting parameters, make co
ntact with a strong-coupling calculation of the critical temperature.
Further, the scaled conductivity data show clear evidence for a thermo
dynamic transition along the freezing line H(m)(T) is-proportional-to
(1 - T/T(c))4/3.