New R-matrix calculations are presented for electron excitation of atomic calcium. The target state expansion includes 22 states: 4s2 1S; 4snl1,3L, where nl is 3d, 4p, 5s, 5p, 4d and 4f; 3d4p1,3P,D,F; and 4p2 3P, 1D, 1S terms. The calculation is in LS coupling, and configuration interaction involving 3p subshell correlation is included. Electron impact excitation cross sections from the 4s2 ground state to the next 10 states are tabulated for low energies, and thermally averaged effective collision strengths are tabulated over a range of electron temperatures from 1000 to 10,000 K. Comparisons are made with previous cross sections calculations for the 4s2−4s4p3P° transition; excellent agreement is found with experimentally derived rates for 4s2−4s4p1P°.