Tropical seaweeds represent a major source of diversity and potential for cultivation. Cultivation of seaweeds has been coined “phyconomy” (derived from phycology and agronomy). One of the world’s most important groups of tropical seaweeds is the eucheumatoids (comprising members of the genera Kappaphycus and Eucheuma). Whilst the biomass from these seaweeds is mostly used to produce colloids (i.e., various carrageenans) trends are changing and new, value-added applications are emerging including bioactives for agriculture, pharmaceutical applications, as well as bioplastics and possibly energy when processed as part of a MUZE (i.e., multi-stream, zero effluent), or biorefinery approach. Phyconomic activities around the production of seaweed biomass provides socio-economic benefits for many hundreds of thousands of global, coastal dwellers around a circum-tropical belt. However, times are changing and the once, repetitive manual aspects of attaching seaweed fragments to ropes and nets is beginning to be mechanized. Whilst it has taken agronomy several thousands of years to develop on land, its phyconomic counterpart is, at best, 50 years old in relation to developments in cultivation of eucheumatoids. Activities around cultivation of these tropical seaweeds can contribute to achieving the UN Sustainable Development Goals. This book contains contributions from many of the world’s authorities on tropical seaweed farming with a focus on the eucheumatoids. There are many lessons learned and best-practice examples which will be of interest to students of phyconomy (phycology), marine science, industrial users of cultivated biomass, as well as practitioners in charge of coastal zone management and ensuring responsible and sustainable socio-economic benefits are derived from marine resources for coastal dwellers.