  We study the $S$-matrix interpretation of quantum theory in light of
Categotical Quantum Mechanics. The $S$-matrix interpretation of quantum theory
is shown to be a functorial semantics relating the algebras of quantum theory
to the effective $S$-matrix formalism. Consequently, issues such as state
reduction and entanglement generation can be depicted in a simple manner.
Moreover, this categorical $S$-matrix interpretation does not have the alleged
thermodynamic cost.
