  This paper provides a systematic study of supergravity contributions relevant
for inflationary model building in Jordan frame supergravity. In this
framework, canonical kinetic terms in the Jordan frame result in the separation
of the Jordan frame scalar potential into a tree-level term and a supergravity
contribution, which is potentially dangerous for sustaining inflation. We show
that if the vacuum energy necessary for driving inflation originates dominantly
from the F-term of an auxiliary field (i.e. not the inflaton), the supergravity
corrections to the Jordan frame scalar potential are generically suppressed.
Moreover, these supergravity contributions identically vanish if the
superpotential $W$ vanishes along the inflationary trajectory. On the other
hand, if the F-term associated with the inflaton dominates the vacuum energy,
the supergravity contributions are generically comparable to the globally
supersymmetric contributions. In addition, the non-minimal coupling to gravity
inherent to Jordan frame supergravity significantly impacts the inflationary
model depending on the size and sign of this coupling. We discuss the
phenomenology of some representative inflationary models, and point out the
relation to the recently much discussed cosmological `attractor' models.
