Using the manifestly spacetime-supersymmetric version of open superstring f
ield theory, we construct the free action for the first massive states of t
he open superstring compactified to four dimensions. This action is in N =
1 D = 4 superspace and describes a massive spin-2 multiplet coupled to two
massive scalar multiplets. (C) 1999 Published by Elsevier Science B.V. All
rights reserved.