The frequency-degenerate two-photon absorption (TPA) in glutathione-capped colloidal CdTe quantum dots with a dot radius ranging from 1.5 to 2 nm, which belongs to the regime of very strong quantum confinement, is determined unambiguously by utilizing the Z-scan technique with femtosecond laser pulses. At laser wavelengths between 720 and 950 nm, the TPA cross sections are measured to be of the order of ${10}^{-47}–{10}^{-46}{\text{cm}}^4\text{\hspace{0.17em} s \hspace{0.17em}}{\text{photon}}^{-1}$ , with precise values depending on both the laser wavelength and the dot size. The TPA measurements are in agreement with theoretical modeling based on a spherical eight-band Pidgen and Brown model. The quantitative modeling reveals underlying factors that contribute to both the TPA–size relationship and size dispersion effects.