In this paper we show how text, context and prosody of discourse markers reflect cognitive and discourse phenomena of uncertainty and certainty, intensity of emotional response, and interactive signals of knowledge state. We demonstrate how the subtle and finely differentiated meanings permeating spontaneous speech are communicated by prosodic variations and that it is the differences in shape that communicate the degree of uncertainty or certainty with respect to the speaker’s knowledge state, and cognitive status. We then propose a tripartite model of prosody and discourse markers to account for the contextual determination of discourse maker interpretation.