This Chapter focuses on molecular logic which goes outside the classical Boolean blueprint of 0 and 1. Instead of binary, we now encounter ternary and higher logics. The latter logics gain information density by sacrificing robustness. However, experimental conditions are arranged in specific instances so that the robustness problem is avoided. Instances where the output signal switches in an ‘off-on-off’ manner form the bulk of molecular examples which are currently available. Although less dramatic in behaviour, output signal patterns of ‘low-medium-high’, ‘high-medium-low’, ‘medium-low-high’ and ‘high-medium-high’ are also documented. ‘On-off-on’ cases form a smaller set, whereas ‘off-on-on’ versions deal with two distinguishable ‘on’ states. An important application of ternary and higher logic, molecular computational identification, is held back until Chapter 14.