Abstract: Nuptial gift-giving has been documented in several taxonomic groups such as insects, snails, birds, squid, arachnids and humans. Although this trait has evolved many times independently, no general framework has been developed to predict the conditions necessary for nuptial gift-giving to evolve. Here, we use a time-in time-out model to derive analytical results describing the requirements necessary for selection to favour nuptial gift-giving. Specifically, selection will favour nuptial gift-giving if the fitness increase caused by gift-giving exceeds the expected gift search time times the encounter rate of the opposite sex. Selection will favour choosiness in the opposite sex if the value of a nuptial gift exceeds the inverse of offspring processing time multiplied by the rate at which mates with nuptial gifts are encountered. We test these results using an individual-based model applied to a system of nuptial gift-giving spiders, Pisaura mirabilis, by estimating parameter values using experimental data. The results provide a general framework for understanding conditions under which evolution of nuptial gift-giving will occur. Our results also provide novel insight into the evolution of fake or worthless nuptial gifts.