Locality in free string field theory

Free string field operators are constructed for the open bosonic string in the light cone gauge in any dimension. These are naturally localized by the center of mass coordinate. Relative to this localization they are shown to have a causal commutator provided there are no tachyons. For the critical string in d = 26 the result still holds if the tachyon is suppressed. We al so show a causal commutator relative to the "string light cone." (C) 2000 A merican Institute of Physics. [S0022-2488(00)02901-7].