Reports of cooperative behavior among promiscuous species and cooperative performance of pre-nest reproductive activities such as mate attraction, courtship, and copulation are rare. Factors that influence the likelihood of helping behavior occurring in promiscuous species are considered. The occurrence of prenest helping behavior and factors that may have selected against its presence in most species and favored its evolution in the groups in which it is found are discussed. It is argued that help with pre-nest activities should be detrimental to both the helper and recipient in species with lasting pair bonds. RESUMEN. Son raros los informes sobre comportamiento cooperativo entre especies promiscuas y sobre el desempeno cooperativo de actividades reproductivas pre-anidadoras, tales como atracci6n de pareja, cortejo y copulaci6n. Se consideran los factores que influyen en la probabilidad de comportamiento de ayuda que se presenta en especies promiscuas. Se discute la presencia de comportamiento de ayuda pre-anidadora y los factores que pueden haber sido seleccionados en contra de su presencia en la mayoria de las especies y los que pueden haber favorecido su evoluci6n en los grupos en que se presenta dicho comportamiento. Se discute que la ayuda en las actividades pre-anidadoras debe ser detrimente para ambos, el ayudante y el ayudado, en especies con vinculos de pareja perdurables. The literature on cooperative breeding suggests that cooperation occurs much more frequently at some stages of the reproductive cycle than at others. In an overwhelming majority of species, the help provided involves feeding and care of the young, although in some, help with nest building, nest defense, nest sanitation, incubation, and territory defense is reported also. At the same time, the distribution of helping behavior among species with different types of mating systems is not uniform. So far, cooperative breeding has been reported primarily for monogamous species with Type A territories (i.e., those in which courtship, copulation, nesting, and feeding occur, Nice 1941), although helping in colonial nesters (e.g., Fry 1975; Dow 1977; Balda and Balda 1978; Emlen 1982) and polyandrous species (e.g., Maynard Smith and Ridpath 1972; Ridpath 1972; Mader 1979; Birkhead 1981) is also known. In all of these species males and females share duties at the It is not surprising that most help reported involves nest-related activities. When Skutch (1935) first reported the phenomenon, he dealt only with helpers at the nest. In fact, there is no a priori reason why help could not be rendered with any reproductive process, including pre-nest activities, or in species with any type of mating system, yet, reports of cooperative behavior among promiscuous species, and cooperation with mate attraction, courtship, and copulation, are rare. Interestingly, help with these particular pre-nest activities has been reported only from promiscuous species, and promiscuous species (with one exception, Dow 1977) have been reported to exhibit only this type of help. In fact, the primary basis of this relationship may not be the type of mating system, per se, but rather, the associated characteristic of pair-bond length, or length of the male-female association. In the present paper, I consider factors that influence the likelihood of various types of helping behavior occurring in promiscuous species as well as the likelihood of help with mate attraction, courtship, and copulation occurring in species with different types of mating systems. I argue that selection should favor help with pre-nest activities among forms with transient bonds (most promiscuous species), but that its occurrence should be detrimental to both the helper and recipient in species with lasting pair bonds (most bird species).