  We present mid-infrared imaging and far-infrared (FIR) spectroscopy of 5 IBm
galaxies observed by ISO as part of our larger study of the inter- stellar
medium of galaxies. Most of the irregulars in our sample are very actively
forming stars. The mid-infrared imaging was in a band centered at 6.75 microns
that is dominated by polycyclic aromatic hydrocarbons (PAHs) and in a band
centered at 15 microns that is dominated by small dust grains. The spectroscopy
of 3 of the galaxies includes [CII]158 microns and [OI]63 microns, important
coolants of photodissociation regions (PDRs), and [OIII]88 microns and [NII]122
microns, which come from ionized gas. [OI]145 microns and [OIII]52 microns were
measured in one galaxy as well. These data are combined with PDR and HII region
models to deduce properties of the interstellar medium of these galaxies.
