The Detached Binary TW Coronae Borealis

New radial velocity and photometric data for TW CrB have been obtained, and Roche-based simultaneous analysis of RV and light curve data for the system has been accomplished for the first time, using the 2003 version of the Wilson-Devinney code. Values for the masses and radii have been obtained: M1 = 1.31 (6) Mʘ, M2 = 1.22 (4) Mʘ, and R1 = 1.50 (1) Rʘ, R2 = 1.42 (1) Rʘ. For the luminosities the most likely values are L1 = 2.78 (5) Lʘ and L2 = 2.01 (4) Lʘ. Both stars are likely unevolved. There is general agreement with earlier photometric values for Zhang and Zhang (2003) with the exception of their masses and mass ratio. Because the values in this paper for the latter quantities are based on radial velocities, they are to be preferred.