There are a number of nonhuman animal welfare monitoring schemes for animals on the farm in Australia and in other countries. Although the majority of such schemes are voluntary rather than legislated, some are nevertheless enforced through a number of customer requirements that industries must meet to gain access to markets. Animal welfare monitoring schemes rely on a number of measures, but the majority are based on simple measures of resource or management inputs with fewer animal-based measures; few are specific to animal welfare outcomes. Furthermore, most measures are used retrospectively, particularly where there has been a problem, to improve welfare for the next "batch" of animals and thus few measures can be used to predict animal welfare outcomes with these schemes. There is considerable uncertainty about the concept and consequently the measurement of animal welfare. Science has a clear contribution to make in forging better agreement on animal welfare assessment and also has important roles in both developing practical animal-based measures of animal welfare and validating that animal welfare monitoring schemes are worthwhile in improving at least some aspects of animal welfare.