Breit-Pauli results for energy levels, lifetimes, and some transition data are reported for all levels of the 2s², 2s2p, 2p², 2s3s, 2s3p, and 2s3d configurations of the Be-like spectrum for 4 Z12. A simultaneous optimization scheme was applied so that a radial basis could be determined for a set of terms that mix in the Breit-Pauli approximation. Convergence of the LS line strength is used as a factor in estimating accuracy as well as the agreement of energy levels and their splitting between theory and experiment. The results are evaluated by comparison with other theoretical results and experiment for transition rates.