  We have made observations of 98 low-Galactic-latitude pulsars to measure
pulse broadening caused by multipath propagation through the interstellar
medium. Data were collected with the 305-m Arecibo telescope at four radio
frequencies between 430 and 2380 MHz. We used a CLEAN-based algorithm to
deconvolve interstellar pulse broadening from the measured pulse shapes. We
employed two distinct pulse broadening functions (PBFs): PBF$_1$ is appropriate
for a thin screen of scattering material between the Earth and a pulsar, while
PBF$_2$ is appropriate for scattering material uniformly distributed along the
line of sight from the Earth to a pulsar. We found that some observations were
better fit by PBF$_1$ and some by PBF$_2$. Pulse broadening times ($\tau_d$)
are derived from fits of PBFs to the data, and are compared with the
predictions of a smoothed model of the Galactic electron distribution. Several
lines of sight show excess broadening, which we model as clumps of high density
scattering material. A global analysis of all available data finds that the
pulse broadening scales with frequency, $\nu$, as $\taud \propto\nu^{-\alpha}$
where $\alpha\sim 3.9\pm 0.2$. This is somewhat shallower than the value
$\alpha=4.4$ expected from a Kolmogorov medium, but could arise if the spectrum
of turbulence has an inner cutoff at $\sim $300--800 km. A few objects follow
particularly shallow scaling laws (the mean scaling index $\meanalpha \sim 3.1
\pm 0.1$ and $ \sim 3.8 \pm 0.2$ respectively for the case of PBF$_1$ and
PBF$_2$), which may arise from large scale refraction or from the truncation of
scattering screens transverse to the Earth--pulsar line of sight.
