Purpose: Long-term sickness absence is a significant human and economic cost in many countries, including Sweden making research on factors which impact on return to work (RTW) relevant. This study has two aims: (1) provide an overview of factors that impact RTW expectations in a national sample of Swedish workers on long-term sickness absence; and (2) gain an understanding of the interrelationships among these factors using a socioecological framework and decision tree analysis. Method: A survey, designed to capture information about demographic variables, health and work ability, workplace contact, supervisor support and expectations of return to work, was mailed to 1,112 randomly selected sick-listed people in Sweden and completed by 534, representing a response rate of 48%. Results: The most important factors affecting RTW expectations were work ability and burnout. Employees reporting high levels of work ability were more likely to expect to RTW compared to those reporting low levels, and this was dependent on their relative burnout score. Those with a high burnout score were less likely to expect to RTW, while for those with a low burnout score RTW expectations were dependent on age, country of birth, and supervisor support. For young employees reporting low work ability and low burnout score, RTW expectations were lower. Conclusions: Our results suggest a more nuanced approach to delivery of RTW services is required, whereby practitioners need to understand the socioecology of the range of factors that impact RTW expectations. The use of decision tree analysis facilitates this understanding by describing the interrelationships between these factors.