Standard Monte Carlo and the recently developed dynamic Monte Carlo (DMC) techniques, together with the COSMIC(90) molecular mechanics force field, are applied to conformational space searching for a number of multi-molecular systems. Specifically, the systems modelled are liquid water, octacyanospherand dihydrate, and two complexation studies based on macrocyclic crown ether hosts with protonated amine guests. These systems are chosen not only to demonstrate the effectiveness of the COSMIC(90) force field and DMC as a global minimum hunter, but also as preliminaries for determining 3D aqueous solution conformations of more complex biomolecules. The performance of the COSMIC(90) force field in simulating liquid water, using Monte Carlo, is assessed against other, highly optimized, models. DMC modelling of octacyanospherand - a complexing agent for salts - with two water molecules results in a structure with a slightly distorted symmetry from the crystal data. Simulations of the macrocyclic hexaether host, 2,3:4,5-bis[1,2-(3-methylnaphtho)]-l,6,9,12,15,18-hexaoxacycloeicosa-2, 4-diene, with tert-butylammonium ion gave particularly encouraging results. For this system unconstrained modelling successfully located host-guest inclusion complexes, in reasonable agreement with crystal data. A chiral recognition modelling study was also performed on a Cram dinaphthyl macrocyclic crown ether host with enantiomers of the amino ester ion PhCH(CO 2Me)NH 3 +. Again the unrestrained DMC simulations located bound host-guest inclusion complexes. Calculations show a preference for the S-complex over the R-complex, in qualitative agreement with experiment.