We show that assemblies comprising anchored polymers with a gradual variation of graftingdensities on solid substrates can be generated by first covering the substrate with a molecular gradientof the polymerization initiator, followed by polymerization from the substrate-bound initiator centers(“grafting from”). We apply this technique to prepare grafting density gradients of poly(acrylamide) (PAAm)on flat silica substrates. We demonstrate that using the grafting density gradient geometry, the mushroom-to-brush transition can be accessed on a single sample. This transition is detected by monitoring thedependence of the thickness of the grafted PAAm in a good solvent using variable angle spectroscopicellipsometry. Wettability experiments performed on the gradient PAAm substrate provide complementaryinformation about the nature of the mushroom-to-brush transition.