  The dust in the interstellar medium, that provides the material for forming
stars - and circumstellar discs as a natural by-product - is known to have
submicron sizes. As these discs are the sites of planet formation, those small
grains are predicted to grow to larger entities when the stars are still young.
will review evidence for the first steps in grain growth in proto-planetary
discs around young stars, based on recent Spitzer and ground-based infrared
observations. First, I will discuss disc and dust properties in Herbig Ae/Be
stars, and then move to the lower-mass T Tauri stars and the brown dwarfs.
Here, objects of different star-forming regions are compared, and the influence
of the stellar parameters and environment on dust evolution, as witnessed by
the observed dust characteristics, is discussed.
