Reproduction of newly established populations of the warm-water Atlantic Mediterranean wrasse Thalassoma pavo is here reported for the first time in the Ligurian Sea, and mating behaviour is described in detail. The reproductive season (May to October) may be divided in three stages: (1) pre-mating (mid-May to the end of June), during which terminal-phase (TP) males establish territories and start courting females; (2) mating (end of June to the end of August), with a mean frequency of up to one spawning event ind−1 h−1; and (3) post-mating (September to mid-October), when TP males remained inside territories but no spawning events were recorded. Mating followed two distinct modalities: pair spawning and group spawning, the latter replacing the former when population density exceeded 10 ind 100 m−2. Four phases have been distinguished in both modalities: (1) approach (pair) or gathering (group), to establish the contact between potential partners; (2) acceptance (pair) or priming (group), in which partners establish a common behavioural pattern; (3) ascent to near the sea surface; and (4) spawning. The saddled sea-bream Oblada melanura has been seen to predate intensively on the large cloud of sexual products released by groups.