In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species this pattern is reversed, with more colourful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colourful ornamentation, individual quality and mating success are not well established. The red phalarope (Phalaropus fulicarius) is a colourful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable colour variation. Here, we describe sex differences in colour and quantify associations between colour variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across three consecutive years on the Arctic breeding grounds, we scored colour variation for four body parts (bill, crown, cheek and breast), and analysed scores separately and combined into an overall colour score. Females were more colourful and larger than males, and individuals could be unambiguously sexed by crown colour. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall colour scores. Assortative mating by colour was only found for the bill. Colour variation did not correlate with plasma testosterone levels, except for male cheek colour. Females in better body condition had yellower bills and higher overall colour scores, while early-arriving birds had higher breast and overall scores. Phalaropes that bred locally were heavier than those that did not, but they did not have higher colour scores. Female colour variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, phalarope colour variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success.