In formal work on the meaning of English, intonation with expressive, or (allegedly) emotive, meaning has received little attention, and has been treated as separate from compositional meaning. I argue against this based on data from Japanese, showing that expressive intonation can be part of compositional meaning, hence "grammatical". Focusing on intonation patterns occurring with the Japanese sentence-final particle yo, I propose a compositional analysis of its non-emotive meaning and argue that English intonation carries the same complex meaning-thus, it is within the scope of formal semantics/pragmatics.