The United Nations Sustainable Development Goals (SDGs) highlight the need to combat hunger and improve the well-being of small-scale producers. Small-scale producers significantly contribute to food supply, yet many face food insecurity and vulnerability to climate change and environmental degradation, particularly in sub-Saharan Africa (SSA) and South and East Asia. Farmer organizations (FOs), including associations, cooperatives, and self-help groups, aim to support members' interests by improving access to markets, credit, and services, and by managing shared natural resources. While FOs are central to rural development policies, questions remain about their equity and whether they primarily benefit middle-class farmers. This study addresses the need for more evidence on FO impact to inform effective interventions for achieving the SDGs, particularly targets related to hunger, smallholder income, and environmentally friendly agricultural practices. The study focuses on SSA and India, regions with a long history of FOs, and analyzes 239 studies to assess FOs' contributions to income, empowerment, agricultural production, food security, and the environment.

Several studies have reviewed FOs' contributions to sustainable development, but most focused on specific FO types or countries and lacked a systematic approach. This scoping review builds upon previous work by adopting a broader, more systematic approach to assess the impact of FOs across diverse contexts in SSA and India. The review considers a wide range of FO types and examines their contributions across multiple dimensions of sustainable development.

This scoping review followed PRISMA-SCR guidelines, encompassing five steps: (1) defining the research question; (2) identifying relevant studies using pre-determined definitions (small-scale producers, FOs, FO services, environmental impacts, livelihood impacts, sustainable livelihood); (3) study selection; (4) data extraction and charting; and (5) collating, summarizing, and reporting the results. The search included electronic databases (CAB Abstracts, Global Health, Web of Science Core Collection, Scopus) and grey literature. Inclusion criteria focused on studies explicitly referencing small-scale farmers, FOs, SSA or India, published after 2000, and detailing FO impacts on livelihoods or the environment. A three-stage selection process involved title screening (enhanced by machine learning), abstract screening (using Covidence software), and full-text screening. Data extraction documented study characteristics, FO types, services, impacts, and socio-economic factors. The review synthesized data on FO services and their impacts, considering external and socio-demographic factors. Methodological quality assessment examined sampling methods, use of control groups and pre/post-assessments, and clarity of data analysis methods. The data extraction template documented study type and various aspects of FOs and their membership, including FO types, membership costs, years of operation, focal activities (crops and livestock), and services provided. Impacts were categorized into income, yield, production quality, environment, empowerment, and food security. The presence of external and socio-demographic factors potentially influencing impact was also documented. Data synthesis involved examining FO services and their impacts on livelihoods and the environment in the context of documented external and socio-demographic factors.

The 239 included studies documented FOs in 24 countries, mostly published since 2010. Seven FO types were identified. The most common services were marketing services, access to market information, and extension/educational services. Most studies reported multiple services. Impacts were categorized into six areas: * **Income:** 58% of studies reported positive impacts, primarily from FOs engaged in crop production and with open membership. Marketing assistance and market information were strongly associated with income improvement. Income increases ranged from 3% to 70%. FOs helped stabilize income through market access and bargaining power. * **Production Quality:** Positive impacts were reported in 20% of studies, mostly from crop production FOs with open membership. Marketing information and output marketing were key drivers. * **Yield:** Positive impacts were found in 19% of studies, predominantly in crop production FOs with open membership. Output marketing, extension services, and market information were associated with yield improvements. * **Environment:** Positive environmental impacts (resilience-building, water quality/quantity) were documented in 24% of studies, primarily from natural resource management FOs. Natural resource management and market-related services contributed to these benefits. * **Empowerment:** About 31% of studies focusing on self-help and women's groups (mostly in India) reported improvements in social empowerment. Improvements were measured in terms of confidence, psychological well-being, and decision-making participation. * **Food Security:** Only 8% of studies addressed food security, primarily showing positive impacts from self-help and women's groups in India. External factors influencing FO success included government support (40% of studies reported government support), NGO/donor support (25%), and climate variability (12.6%). Socio-economic factors affecting membership and service delivery included gender, land access, education, poverty, and distance to markets. Marginalized farmers were less likely to benefit from FOs.

The findings highlight the positive contribution of FOs to smallholder livelihoods, particularly in improving income and, to a lesser extent, yield and production quality. Market access services (marketing, information) were crucial for income gains. Extension and educational services were also important across FO types. These results underscore the value of designing FOs with a focus on market access, financial services, and extension services. The review highlights the limited benefits for marginalized producers and emphasizes the need for support systems to improve their capabilities and resources before they can fully benefit from FO membership. Gender inequalities, limited land access, lower education levels, and poverty significantly affect FO participation and benefits. The limited number of studies on food security necessitates further research in this area. The positive environmental impacts from natural resource management FOs suggest that incorporating broader ecosystem management into FO services is crucial for climate change resilience.

This scoping review provides evidence of FOs' positive contributions to smallholder livelihoods and the environment, particularly through improved market access, extension services, and natural resource management. However, benefits are unevenly distributed, with marginalized farmers facing significant barriers to participation and benefitting less from FOs. Future research should explore the heterogeneity of FO impacts among members, investigate spillover effects on non-members, and address the gap in understanding food security outcomes. Policy interventions should focus on strengthening market access, providing financial services, enhancing extension services, incorporating natural resource management, and implementing support systems for marginalized farmers, particularly women.

The review's findings may be influenced by publication bias, as studies reporting positive results are more likely to be published. The sample may not fully represent all FOs and their impacts. The methodological quality of included studies varied, and some studies lacked clear methodological descriptions. While the review analyzed a large number of studies, it did not perform a meta-analysis of the quantitative data, limiting the ability to draw precise quantitative conclusions about the overall impact of FOs.