  These notes describe how perturbative on-shell and off-shell string
amplitudes can be computed using string field theory. Computational methods for
approximating arbitrary amplitudes are discussed, and compared with standard
world-sheet methods for computing on-shell amplitudes. These lecture notes are
not self-contained; they contain the material from W. Taylor's TASI 2003
lectures not covered in the recently published ``TASI 2001'' notes {\tt
hep-th/0311017} by Taylor and Zwiebach, and should be read as a supplement to
those notes.
