  Starting from a relativistic formulation of the pion-nucleon-delta system,
the most general structure of 1/M corrections for a heavy baryon chiral
lagrangian including spin 3/2 resonances is given. The heavy components of
relativistic nucleons and delta fields are integrated out and their
contributions to the next-to-leaing order lagrangians are constructed
explicitly. The effective theory obtained admits a systematic expansion in
terms of soft momenta, the pion mass $m_\pi$ and the delta-nucleon mass
difference $\Delta$. As an application, we consider neutral pion
photoproduction at threshold to third order in this small scale expansion.
