Ethylene/norbornene and ethylene/1-butene copolymerization with nickel(II) salicylaldiminato complexes [{kappa(2)-N, O-6-C(H)dN(2,6-R2C6H3)-2,4-R'2C6H2O}NiMe(pyridine)] (1a, R) 3,5-Me2C6H3, R' = I; 1b, R, R') 3,5-(F3C)(2)C6H3; 1c, R = 3,5-(F3C)(2)C6H3, R' = I; 2, R = Pr-i, R' = I) were studied in toluene as a reaction medium and in emulsion, the latter affording polymer dispersions. High molecular weight copolymers (M-n > 10(4) g mol(-1)) are formed. Incorporation of ethylene is much preferred over butene incorporation, X-Bu/x(Bu) similar to 0.05 under typical reaction conditions, by comparison incorporation of the strained olefin norbornene is higher, X-NB/x(NB) similar to 0.25 (X = comonomer mole fraction in polymer; x = comonomer mole fraction in reaction mixture). Dispersions contained copolymers with up to 6 mol % comonomer (12wt% for 1-butene; 20 wt% for norbornene). Incorporation of a few mol % of norbornene strongly decreases polymer crystallinity, which enhances the film forming properties of dispersions. Microstructure analysis by C-13 NMR shows that butene is incorporated in a 1,2-, 1,3- and 1,4-fashion. Whether 1,2- or 1,3- incorporation is predominant depends on the catalyst ( nature of R).