Near-infrared imaging of IRAS pre-main sequence (PMS) sources
 often show extended structure of cometary or bipolar appearance
 surrounding a point source and extending over about 1000 AU.
 These near-ir extended structures probably result from scattering
 off the walls of an outflow cavity.  The position, size, and
 orientation of the near-IR extended emission correlates very well
 with those of the associated bipolar molecular outflows.  The most
 obscured sources (which are also the youngest) have the highest
 ratio of extended-to-point source flux in the near-infrared, some
 are completely nebulous at K.  These latter objects are the
 reddest IRAS PMS sources, with spectral energy distributions
 peaking at 100 um or longer wavelengths.  Ground based midinfrared
 imaging of young relatively high mass protostars often detect
 extended emission coming from warm dust (100 to 400 K) both in the
 immediate surroundings of the protostar (circumstellar disk) and
 in more extended regions presumably due to small grains heated by
 shock waves within their associated bipolar outflows.  However,
 nobody has done any such imaging projects on low mass protostars
 due to the high sensitivity required, which is not attainable on
 ground-based telescopes.  We propose to obtain high resolution
 multiple wavelength ISOCAM images of the youngest known nearby low
 mass protostars.  This will locate accurately the central sources
 in relation to the outflow cavities and the near-infrared
 reflection nebulae, and allow detailed models of circumstellar
 dust heating during the accretion/outflow phases.  In particular
 it will, for the first time, constrain the infall/outflow geometry
 during the earliest PMS phase for low mass stars.  It will also
 permit a measurement of the heating due to shocks in Herbig-Haro
 (HH) jets and knots which will constrain current models of HH
 emission.