Small-scale aquaculture producers in developing countries are facing new opportunities and challenges related to market liberalization, globalization and increasingly stringent quality and safety requirements for their products, making it harder for them to access markets. Collective action through participation in farmers' organization (FOs) can provide an effective mechanism to assist small-scale producers overcome these challenges ad contribute to and influence modern market chains and trade. This publication presents factors associated with successful FOs and guiding principles for development organizations that wish to support aquaculture FOs in developing countries.