TAURUS MOLECULAR CLOUD: COAGULATION OR MANTLE FORMATION? The Taurus molecular cloud is an important site to study processing of interstellar grains. In my presentation I will be concentrating on our work to decipher the predominant growth mechanism in this cloud. Previous work has shown that mantle formation is observed via absorption profiles of various chemical species and coagulation maybe inferred along those lines of sight that have elevated values of Rv, the ratio of total to selective extinction. To date there has been no systematic study done to observe the existence of lack of correlation between coagulation and mantle formation in dense cloud environments. This work will be a small step in that direction, we have procured 3.1 micron spectroscopic data and visible to IR extinction data along lines of sight to field stars probing different environments of Taurus molecular cloud. Our results show that though mantle formation is the predominant growth mechanism in Taurus, coagulation does occur in very dense region of the molecular cloud. I will also discuss some of our future plans to study processing of grains in the Taurus and Rho Oph molecular clouds.