I use the most recent cosmic microwave background (CMB) anisotropy measurements to constrain the leading cold dark matter models in the Ω m-Ω Λ plane. A narrow triangular region is preferred. This triangle is elongated in such a way that its intersection with even conservative versions of recent supernovae, cluster mass-to-light ratios, and double radio source constraints is small and provides the current best limits in the Ω m-Ω Λ plane: Ω = 0.62±0.16 and Ω = 0.24±0.10. This complementarity between the CMB and other observations rules out Ω = 0 models at more than the 99% confidence level.