Stable reactive aqueous dispersions of functional graft polyorganosiloxanes, well suited for formulation into curable silicone compositions useful in the production of release- and other coatings and paints, comprise the polymerizate of at least one ethylenically unsaturated monomer with a functional polyorganosiloxane which comprises identical or different recurring structural units of formula (I):R.sub.a Y.sub.b X.sub.c SiO.sub.(4-a-b-c)/2 (I)in which the radicals R, which may be identical or different, are each a C.sub.1 -C.sub.18 alkyl radical, a C.sub.2 -C.sub.20 alkenyl radical, or a C.sub.6 -C.sub.12 aryl or aralkyl radical, or halogen-substituted such radical; the radicals X, which may be identical or different, are each a hydrogen atom or a reactive functional group bonded to a silicon atom via an Si-C or Si-O-C linkage; the radicals Y, which may be identical or different, are each an ethylenically unsaturated hydrocarbon radical optionally comprising one or more of the heteroelements O and/or N, and bonded to a silicon atom of the structural unit of formula (I) via an Si-C linkage and reactive with said at least one ethylenically unsaturated monomer; a, b and c are each equal to 0, 1, 2 or 3; and a+b+c=0, 1, 2 or 3; with the proviso that the number of SiO.sub.4/2 units is less than 30 mol % and the number of structural units of formula (I) in which the silicon atom is substituted by a functional group X and/or a radical Y is such that the polyorganosiloxane comprises (i) at least 5 milliequivalents, preferably from 10 to 500 milliequivalents, of X functional groups per 100 grams of polyorganosiloxane of formula (I) and (ii) at least 5 milliequivalents, preferably from 10 to 500 milliequivalents, of Y radicals per 100 grams of polyorganosiloxane of formula (I).