In this proposal we request to observe a sample of high latitude
 clouds for which the observed the 12CO versus I100 (as determined
 from IRAS) correlation dramatically deviate from the general pattern
 observed in our galaxy. The clouds in our target list can be
 classified as (i) IR deficient clouds, (ii) CO deficient clouds (iii)
 clouds with wide CO lines, (iii) clouds with high 25 and 60 micron
 IRAS fluxes. For each of the classes we have selected a best
 representative. We want to obtain deep infrared maps at different FIR
 wavelengths with ISOPHOT to determine the distribution and abundance
 of the dust grains as well as deep [OI] 63 micron and [CII]
 158 micron measurements with LWS to quantify the role of the UV
 radiation field and/or the neutral carbon content. These observations
 should provide constraints to the explanations suggested for these
 anomalies.