Multi-choice experiments on larval settlement of the giant scallop, Placopecten magellanicus (Gmelin), in response to various artificial and natural substrata were conducted in a 1000-1 plastic tank to determine what conditions optimize larval and spat collection under a normal, hatchery-type environment. The first experiment tested a variety of substrata (many of which have been previously used in bivalve spat collection studies) including the following: (1) nylon monofilament of diameters 0.50, 0.75, 1.10, 1.50, and 2.00 mm (N.B. the 0.50-mm diameter monofilament was tested with and without a marine microbial film at the beginning of the experiment (designated as ‘filmed’ and ‘non-filmed’, respectively) whereas all other monofilament treatments and the artificial substrata to follow lacked a microbial film at the start of the experiment), (2) polyethylene onion bag material, (3) polyethylene Astroturf, (4) smooth and roughened clear acrylic plastic, (5) polyester aquarium filter-wool, and (6) filmed and non-filmed adult giant scallop shells. Standardized for surface area, filter-wool collected significantly more larvae and spat than any other non-filmed substratum (Student-Newman-Keuls (SNK) test, P ≤ 0.05). There was no significant difference among all other non-filmed substrata in numbers of larvae or spat collected (SNK test, P > 0.05). Filmed 0.50-mm diameter monofilament and filmed adult shell collected significantly more spat than their respective non-filmed counterparts (SNK test, P < −0.05). A second experiment examined settlement on various types of polyethylene meshes (Vexar) including the following mesh sizes (mm): 3.0, 3.0 × 11.0, 3.8, 7.0, 11.0, and 19.0. All substrata were black except the 3.0-mm mesh which was green. Standardized for surface area, the 3.0-mm mesh collected significantly more larvae and spat than any of the other mesh sizes (SNK test, P ≤ 0.05). There was only one other significant pairwise comparison of numbers of spat collected; 3.8-mm mesh collected significantly more spat per unit surface area than 11.0-mm mesh (SNK test, P <- 0.05). Polyester filter-wool, which was by far the best substratum for spat collection, is inexpensive and re-usable and could make an excellent settling material for use in hatcheries.