In most species, the female frog selects the appropriate calling male and the breeding begins. Sometimes the site that the male is calling from is not a good location for laying eggs. However, he will mount the female anyways. She will usually end up carrying him to the proper nesting site.
Nearly all frogs mate by amplexus. This is a technique widely used by fish. The principle is that, if the two sexes are close enough together and plenty of eggs are released into the water at the same time, enough eggs will be fertilized to make the whole thing worthwhile. The male, who is usually smaller, mounts and grips her tightly either in the armpits or just in front of the hind legs.
The pressure from the male griping the female stimulates the female to release her eggs while the male releases his sperm. The two then mix, and fertilize the eggs. Amplexus also prevents other males from dislodging the male. Often though, amplexus is not as reliable as it seems. It appears that the frogs and toads have about as much trouble telling the sexes apart as we do. Male toads in particular will mount anything that resembles a female toad, including dead toads, the wrong species, inanimate objects, and male frogs.

The mounted male toad will then inform the other of his mistake by giving a series of low volume clicks or chuckles. Females also take advantage of this; they will make the call if they are not ready to release their eggs. Amplexus positions vary as well. Males of some species grip the female just in front of the hind legs, others straddle the female. In some species the size difference is so great that the male just leans against the female.

One species of frog takes mating to the extreme. A male harlequin frog defends his territory all year. When a female appears on his turf, he climbs on board and attempts to breed even if the breeding season is many weeks away. The female, as a result, must carry the male around her back for weeks or even months. This is hard on both parties as the female must carry the male around, and the male gets little to eat. Such extreme commitment to amplexus shows that a male has few opportunities to meet females.