Participation of actors is essential for achievement of the United Nation’s (UN) Sustainable Development Goals (SDGs). With respect to sustainable agriculture the UN has introduced a collaborative framework for food systems transformation encompassing: 1) food system champions identification; 2) food systems assessment; 3) multi-stakeholder dialogue and action facilitation; and, 4) strengthen institutional capacity for food systems governance. The last two actions are the focus of this thesis. Sustainable agriculture involves multiple actors connected horizontally and vertically through agricultural production and supply chain (APSC) networks in which every actors’ decisions and actions are affected by, and affect most, if not, all other actors. Involvement of every actor in the APSCs is essential to enable coordination for sustainable agriculture. Most previous programmes to pursue sustainable agriculture, however, still follow the top-down approach in which local actors are considered as passive entities encouraged to adopt initiatives designed by external actors (e.g. governments, universities, NGOs). Most often, this results in unsustainability of programmes due to the incompatibility of initiatives with factors related to local context. In addition, most programmes focus on horizontal relationships between farmers to deal with encountered challenges, e.g. in production, market, finance. This thesis proposes a different approach that focuses on the participation of actors connected horizontally and vertically in APSCs to (by the actors themselves): analyse situations; design initiatives; and take actions (through working together) to pursue sustainable and workable APSCs. Research through Design (RtD) combined with Action Research, more specifically, Participatory Action Research (PAR) is performed with cases of APSCs in Indonesia, more specifically in the horticultural sector. As most farmers in Indonesia are smallholder farmers (about 93%) with lack of knowledge, information, and capital, Indonesia can be considered to be exemplary for APSCs in developing countries. As most smallholder farmers (including in Indonesia) do not recognise opportunities for sustainable APSCs, empowerment is of importance. This thesis addresses the question: “Can agricultural chain actors (connected vertically and horizontally) in Indonesia be empowered to pursue sustainable APSCs?”. Three concepts that are the foundation of this research are identified: agricultural production and supply chains; empowerment; and co-creation (an approach for empowerment). The first step to answer this question is taking lessons learnt from previous programmes of sustainable agricultural development (SAD) in developing countries. For this, a framework of sustainable APSCs is introduced in this thesis: Participatory Sustainable Agricultural Development (PSAD). The framework focuses on the principles of participation on which most previous frameworks do not focus. This framework was used to analyse previous SAD programmes in developing countries. The results show that, in addition to environmental and economic factors, social factors of empowerment and engagement have shown a positive effect in pursuing sustainable APSCs. In addition, continued facilitation in a follow-up programme is also essential to pursue sustainable APSCs. Based on these results, an approach to empower APSC actors has been designed in this thesis: COCREATE. COCREATE empowers local actors to engage in designing initiatives to be implemented by local actors themselves (through working together) to deal with their situations. For this, pursuing a common understanding of involved actors on their common situations is essential. COCREATE consists of design and implementation activities, and the process of these activities is cyclic with continuous feedback. Reflection is one of the essential elements with which this approach pursues common understanding that most previous approaches do not include. Meanwhile, with respect to actors, COCREATE involves actors that are connected both horizontally and vertically in the APSCs in which power imbalances exist. COCREATE, in this research, was implemented in multiple cases of APSCs in Indonesia, more specifically with local trader-farmer groups and a farmer organisation (FO), more specifically with a group of farmer groups, in which most smallholder farmers were involved. Both cases are located in a horticultural production centre in Indonesia, in Bandung District, West Java. Local trader-farmers groups, representing the primary vertical relation in the chain, consist of a local trader and farmers connected through traditional chain governance (i.e. local trader provides finance to farmers, consequently farmers must sell all their produce to the local trader). Even though they depend on each other in their APSCs systems, there is lack of incentive alignment in their relationships. In fact, many problems arise due to, e.g. lack of information transparency, unfair chain governance, lack of commitment. Meanwhile, an FO, representing horizontal relations in the chain, consists of farmers connected through organisational governance to enable them to do collective actions, including getting access to markets. The FO in this case is a group of farmer groups (GFG) that faced challenges of the commitment of farmer members, internal information flow, bottlenecks in the production and supply chain, and, financial arrangements as a consequence of the growth in market and membership (also known as being successful). In the implementation of COCREATE with cases of both local trader-farmers groups and a GFG, participants were able to apply the sequence of procedure in design activities, including reflection. It resulted in common understanding improvement of involved actors of their situations that can be seen from solutions co-created and agreed by them. In the implementation activities, participants (in cases of local trader-farmers groups and GFG) were able to organise themselves to implement agreed solutions. Meanwhile, in the follow-up design, they were able to evaluate and adapt the solutions to address the changes in situations. Facilitators, in both cases, played important roles to ensure the procedure of COCREATE (including reflection) was implemented appropriately supporting participants by providing the information needed and facilitating access to external parties when asked to by the participating actors. In the case of local trader-farmers groups, COCREATE implementation resulted in a change in relation and task division between farmers and local traders (in each group), improving market position and institutional arrangements between them. Meanwhile, in the case of a GFG, COCREATE implementation resulted in the ability of the GFG to self-organise their governance to deal with the challenges identified. Based on the results, this thesis concludes that: 1) social factors of empowerment and engagement are essential to pursue sustainable APSCs, in addition to environmental, economic and governance factors; 2) COCREATE is an approach to empower APSCs actors (connected horizontally and vertically) in developing countries to engage in pursuing sustainable and workable their APSCs; 3) COCREATE supports farmers and local traders (in the vertical relationships) to improve their own and each other position in the APSCs; 4) COCREATE supports farmer organisation (in the horizontal relationships) to self-organise their governance to maintain sustainable inclusion; 5) Empowering agricultural chain actors in developing countries is a long-term process and requires new approaches within, e.g. extension programmes, local university programmes as well as private business interventions.