We propose to obtain images of reflection nebulae with ISOCAM
 and the circular variable filter (CVF), in order to determine
 the spatial distribution of specific infrared emission features
 (IEFs) within each nebula.  Our sample includes reflection
 nebulae with Tstar, the temperature of the illuminating star,
 ranging from 3,600 K to 33,000 K.  We will obtain CVF images in
 IEFs at 6.2, 7.6, 8.6, and 11.2 um; CVF images at 7.0, 8.3, and
 12.0 um to study broad spectral features at 6-9 um and 11-13 um;
 CVF images at continuum wavelengths of 9.5 and 10.5 um; and
 broad-band continuum images at 4.5 um (LW1) and 15.0 um (LW9).
 Our goals are to (1) compare the spatial distributions within a
 reflection nebula of different IEFs, other broad spectral
 features, and the continuum in order to determine whether these
 features have a common origin; (2) determine the photon energies
 required to excite each spectral feature and the infrared
 continuum by obtaining ISOCAM images with the CVF in reflection
 nebulae with widely varying Tstar; (3) compare ISOCAM images
 of infrared continuum emission to ground-based images of extended
 red emission; (4) compare the spatial distributions of IEFs and
 molecular hydrogen emission within a reflection nebula.  Each
 of these observations, described in more detail below, will be
 compared to model predictions for polycyclic aromatic molecules,
 hydrogenated amorphous carbon grains, and other laboratory
 materials.  ISOCAM observations are needed because of its superb
 sensitivity to low surface brightness mid-infrared emission,
 which is far higher than the sensitivity achievable from
 ground-based or airborne telescopes whose background thermal
 emission peaks in the wavelength region of interest.