This contribution describes catalytic tandem C-N and C-C bond-forming reactions involving the intramolecular hydroamination/bicyclization and intermolecular hydroamination/cyclization of olefins and alkynes using the organolanthanide complexes Cp'(2)LnCH(SiMe3)(2) and Me2SiCp "(2)LnCH(SiMe3)(2) (Cp' = eta(5)- Me5C5; Cp " = eta(5)-Me4C5; Ln = lanthanide) as precatalysts. In the case of the intramolecular processes, substrates of the structures RC=C(CH2)(a)NH(CH2)(b)C=CR, RC=C(CH2)(c)NH(CH2)(d)CH=CH2, and H2C=CH-(CH2)(e)NH(CH2)(f)CH=CH2 are regiospecifically bicyclized to the corresponding pyrrolizidine and indolizidine skeletons, with turnover frequencies ranging from 2 to 777 h(-1) at 21 degrees C and isolated product yields ranging from 85 to 93%. In the case of e = 3 and f = 1 mediated by Cp'Sm-2-, the kinetic rate lawis zero-order in substrate concentration and first-order in lanthanide concentration. In the case of R = Ph, c = 3, and d = 1, the Cp'(2)Ln-catalyzed turnover frequencies fall precipitously with decreasing Ln(+3) ionic radius. In the intermolecular processes, substrates of the type HC=CCH2NHR undergo regiospecific coupling and cyclization to the corresponding pyrroles MeCC(H)=C(<(CH)over bar>2NHR)N(R)CH with high turnover frequencies where R and N-t (h(-1)) are the following: CH2=CHCH2, 236 (60 degrees C); CH3CH2CH2, 208 (60 degrees C); CH2=CHCH2CH2CH2, 58 (60 degrees C). In addition, hydroamination/cyclization processes after intermolecular insertion can be effected when R = CH2=CHCH2, to afford a 2,7-dimethyldipyrrolo[1,2-a:1',2'-d]pyrazine derivative via two successive intramolecular olefin insertion processes. The mechanism for such tandem C-N and C-C bond formations is postulated to involve turnover-limiting intra-or intermolecular alkene/alkyne insertion into the Ln-N functionality, followed by rapid intramolecular insertion of a pendant C=C/C=C-containing functionality into the resulting Ln-C bond (prior to protonolysis). Such a scenario is consistent with well-documented, stepwise transformations in organo-f-element-catalyzed insertions of unsaturated carbon-carbon multiple bonds into metal-amide and metal-alkyl functionalities.