Migrant friendly health services including interpreting services have been implemented worldwide with an aim to reduce language and cultural barriers between healthcare personnel and migrants. Thailand has implemented migrant-friendly service initiative which includes migrant health worker (MHW) and migrant health volunteer (MHV) programs. MHWs and MHVs are expected to serve as key personnel that help relay health message to the wider migrant population. According to this role, health literacy is an essential skill of MHWs and MHVs. However, previous evidence about factors affecting health literacy of migrant workers were not specific to MHWs and MHVs and the evidence in Thailand was quite sparse. This research therefore sought to explore factors affecting health literacy of MHWs and MHVs especially in the angles of health-information access, understanding and appraisal. The researchers applied a parallel mixed method design in Samut Sakhon and Ranong, Thailand. In qualitative part, we conducted in-depth interviews with various stakeholders. The interviewees, selected by purposive and snowballing samplings, comprised MHWs, MHVs, healthcare staff in public health sectors and non-governmental organizations (NGOs) and policymakers. Document review was also employed. Data were analyzed by deductive thematic analysis technique. In quantitative part, primary survey was conducted on 235 participants (MHWs, MHVs and general migrants combined). All MHWs in each study site, MHVs under MOPH provision in Samut Sakhon and MHVs under NGO provision in Ranong were included in the survey. General migrants in the neighborhood area of MHWs and MHVs were randomly selected by a factor of one. Quantitative data analysis was composed of descriptive statistics, t-test, ANOVA, and multiple regression. The study revealed that MHWs had higher health literacy level than general migrant workers due to participating more in intensive training course, and having greater opportunities to receive health information from public health personnel. The strengths of MHW/MHV program were a support of standardized training curriculum and instructional media from the Ministry of Public Health (MOPH). Some organizations used nonfinancial incentives, such as volunteerism and health knowledge seeking behavior as selection criteria for recruiting MHWs and MHVs. However, there were rooms to be improved--including uncertainty of the budget used for employing MHWs and MHVs and a lack of monitoring and evaluation system on MHWs and MHVs. With all accounts above, three key policy recommendations came out. Firstly, the MOPH should make clear of the budget used for for MHW/MHV employment and capacity building. Required capacities for MHWs should be set up; such as communication skills, medical-term understanding, cultural competency, and health literacy. This will also shape the selection process of MHWs. For example, MHWs might be recruited from high-skilled migrant workers before entering Thailand. Secondly, the training courses and monitoring and evaluation processes should be systematically developed based on mutual agreement from all stakeholders. Lastly, non-financial incentives should be focused such as social recognition, healthcare privilege and fringe benefits regarding capacity development should be in place. This will help maintain MHWs and MHVs in the system.