Martian craters defined as fresh on the basis of morphologic parameters have been analyzed for the presence and abundance of various morphologic features as a function of size. Bowl-shaped craters dominate the fresh crater population below about 15 km. The onset of central peaks occurs at about 5 km. Craters above about 15 km often have terraced walls, central peaks, and hummocky floors; at diameters of 40 km and greater, these features dominate fresh martian crater morphology. Central peak onset occurs at smaller diameters on Mars and the Moon than on Mercury, and terrace onset occurs at similar diameters on the Moon and Mars, but at larger diameters than on Mercury. Since Mars and Mercury have a similar surface gravitational acceleration (greater than twice that of the Moon), gravity-controlled crater features should appear at similar diameters on the two planets. However, the differences in onset and abundances of central peaks and terraces on Mars and Mercury indicate that processes other than gravitational effects may also be important.