Polycyclic trisaminomethanes of the formula ##STR1## in which R.sup.1 and R.sup.2, alike or different, are alkylene; R.sup.3 and R.sup.4, alike or different, are alkyl, cycloalkyl, or aralkyl; or R.sup.3 and R.sup.4 are joined together to form an alkylene group which may be interrupted by (1) ##STR2## WHERE Q is hydrogen or alkyl, or (2) ONE OR TWO --O-- linkages; and There are at least 2 carbons between each two hetero atoms in the outer ring system, are useful as initiators for the polymerization of pivalolactone. These polycyclic trisaminomethanes are prepared by reacting a polyamine of the formula R.sup.3 NHR.sup.1 NHR.sup.2 NHR.sup.4 with a dialkoxy(dialkylamino)methane of the formula (RO).sub.2 CHNR'.sub.2 in which R and R', alike or different, are alkyl.