Abstract: The present invention provides novel siloxane iniferter compounds, block copolymers made therewith, and a method of making the block copolymers. The siloxane iniferter compounds can be represented by the formula ##STR1## wherein T and X are organic groups selected so that the T-X bond is capable of dissociating upon being subjected to an appropriate energy source to form a terminator free radical of the formula T.multidot. and an initiator free radical;R.sub.1, R.sub.2, R.sub.5 and R.sub.6 are monovalent moieties selected from the group consisting of hydrogen, C.sub.1-4 alkyl, C.sub.1-4 alkoxy and aryl which can be the same or are different;R.sub.3 and R.sub.4 are monovalent moieties which can be the same or different selected from the group consisting of hydrogen, C.sub.1-4 alkyl, C.sub.