Coralline algae play a central role in tropical reef ecology helping to build and stabilise the reef framework. Due to their high Mg-calcite skeleton, coralline algae are also one of the most sensitive marine calcifying organisms to ocean acidification, and potential indicators for assessing the impacts of climate change. However, despite their importance in reef ecology, basic information on coralline algae, such as their growth and calcification rates, are relatively unknown. The reason for this scarcity of information is, in part, due to the lack of effective and efficient methods for obtaining these rates in the field, and the slow growth of coralline algae necessitating lengthy studies. Therefore, the aims of this study were to establish more effective methods to determine in situ growth and calcification rates of coralline algae, to determine baseline growth and calcification rates of a key reef-building coralline algae species on the Great Barrier Reef (GBR), and to investigate the effects future climate change scenarios may have on these growth rates.