The following extended abstract can be retrieved by anonymous ftp from boole.stanford.edu, IP address 36.8.0.65. Instructions for retrieving this and other papers may found in /pub/README. Contact me, pratt@cs.stanford.edu, if you need further assistance or would prefer to receive a copy by email. Concurrent Automata and Their Logic A concurrent automaton is a poset with a top (the global initial state) and all nonempty sups (the local initial states). These form a nondegenerate self-dual category Aut admitting universally definable operations constituting a concurrent programming language and additional operations yielding a linear logic of concurrency. The automaton ?a is a power set whose dual !a is a free automaton, obtainable from ?a by moving the empty set to the top. The linear logic theory Th(CSLat) of complete semilattices strictly extends Th(Aut), having no counterexample to ?a=!a since ?a and !a are both power sets on the underlying set of a but for dual reasons. Both theories strictly extend linear logic with such howlers as 0=1; these but not ?a=!a are removable by intersecting with classical logic, equivalent to taking both sides of the respective dualities as a single model. This makes Aut a particularly simple model of linear logic. The self-duality of both categories facilitates a noncategorical account requiring only elementary lattice theory for a complete understanding. Vaughan Pratt