Animal sex roles, in a wide sense, were the focus of astimulating post-symposium of the International Society of Behavioral Ecology (ISBE) meeting in Perth 2010. The sex roles symposium consisted of short presentations and anhour of role-play designed to promote refreshed thinking and discussion of “the ecology of sex roles”. In a strict sense, sex roles are defined according to which sex that competes most for matings (Vincent et al. 1992). Here, several contributors discussed empirical findings of flexibility in sex role behaviour, also including mate choice, in relation toecological, social and demographic factors. We discussed theuse fulness of the term “sex roles” and the assumptions often associated with the terminology. The notion that variation within and between individuals - irrespective of their sex –may paradoxically account for sex roles was a theme of the discussions. We discussed empirical findings showing that mate choice and mating competition are flexible in response to ecology, social circumstances, and internal factors in both males and females of a taxonomically wide array of animals.Theory development is accompanying the empirical trend and is emphasizing the adaptive benefits of individually flexible mating decisions. We concluded that variation in mating competition and mate choice seems ubiquitous, and pointed out future directions for the investigation of ecological effects on individual reproductive decisions and competition.