 In this brief overview, I describe one aspect of Avicenna's truth-conditions for modal propositions which became common doctrine among later Arabic logicians. I go on to examine some of what Avicenna said about the subject term of a proposition, and some of the inferences he defended. Avicenna's doctrines on both subject term and modal inferences became much-debated issues in thirteenth-century logic; I follow one line of the debate.