Mating behaviour in Helix aspersa has three major components: introductory behaviour, dart shooting, and copulation. Introductory behaviour, which includes reciprocal tactile and oral contacts, lasts an average of 33.7 ± 23.3 (SD) min. Dart shooting, the pushing of a calcareous dart into the mating partner's body, occurs once for each snail per mating sequence. Snails that hit their partners during the first dart-shooting event copulated 14.5 ± 8.7 min after dart shooting, whereas snails that missed their partners took 40.5 ± 37.5 min to copulate. Dart shooting may facilitate mating by increasing behavioural synchrony. Copulation is reciprocal and has a duration of 421.8 ± 56.6 min. Spermatophores are transferred approximately 300 min after simultaneous intromission. There are significant differences in the mating behaviours of Helix aspersa and Helix pomatia.