Smallholders, who cultivate ±30% of the global palm oil land, are critical to the realization of a sustainable palm oil sector. However, particularly independent smallholders, untied to mills, lag behind in yields and experience challenges to market their produce. Sustainability certification, such as by the Roundtable on Sustainable Palm Oil (RSPO), is proposed as a way to improve smallholder livelihoods, while protecting the environment. However, independent smallholders experience barriers to obtain certification. Through interviews with 18 RSPOcertified independent smallholder groups in Indonesia and 9 certification facilitators, this study examines how pre-certification conditions regarding smallholders’ socio-economic backgrounds, legality, group organization, planation management practices, and local supply chain conditions impact prospects for RSPO certification, and how groups who successfully achieved certification have dealt with challenges during the certification process. We found that the majority (77%) of RSPO certified independent smallholders in Indonesia consists of ‘former scheme’ smallholders. These smallholders often have clear land legality and are organized in groups prior to certification, which increases their eligibility for RSPO certification. However, due to upfront and recurrent costs for certification, as well as complexities in meeting RSPO standards, access to certification is strongly dependent on external facilitators. To up-scale certification for independent oil palm smallholders, and include more nonscheme smallholders, certification projects should involve more local actors including local governments and certified smallholder groups. In addition, certification should focus on core social and environmental concerns for smallholders, while being flexible with regards to the forms of proof needed to fulfil legality requirements.