The primary aim of this study was to explore the Socio-economic impact of circular migration in Kilolo District from the 1960s to 2000s. It specifically intended to analyze the historical factors behind circular migration and to assess the socio-economic impact of circular migration in this district. Additionally the study anticipated to explore how and why circular migration came to a decline from 2000s. Throughout the study the focus was Kilolo district (part of the former Iringa rural) involving keen scrutiny of events that lay behind circular migration and their socio-economic impact in this area during post-colonial Tanzania. In order for the study to be resourceful, a qualitative research approach and a case study strategy were employed in data collection, organization and analysis. A case study strategy was purposively used because it provided ample room for a researcher to study a phenomenon at greater detail. Furthermore to ensure validity and reliability of the research instruments, multiple data collection methods were used to supplement each other. Such research instruments included in-depth interview, focus group discussion (FGD) and documentary review. Key respondents for this study included male adults born between 1930 and 1970s and women married to the migrants as well as retire village Executive officers and Chairmen. These respondents were sampled through purposive sampling and snowball sampling procedures. The data then were organized thematically based on specific objectives and were eventually subjected to content analysis. The findings revealed that circular migration bears its roots from colonial undertakings and the legacy remained and kept haunting the post-independent Tanzania. Notable causes include hardness of life associated with hunger, poor prices of crops, absence of agricultural inputs, poor infrastructure, head tax, economic development plans that entailed coercive forces and poor schooling among others. The study also revealed that circular migratory tendency apart from little temporary benefit to the families particularly in the period of crisis; it has perpetuated miserable poverty, led to spread of sexually transmitted diseases, marriage instability and food shortage due to absence of men, to mention few. Circular migration phenomenon at Kilolo appears to be a remnant of colonial labour migration, and after independence it slightly took new form while still maintaining similar socio-economic impact. In a nutshell, the study is organized into five chapters. Chapter one gives the background of circular migration and its context, and chapter two is occupied by literature review. Chapter three dealt with the methodology used where chapter four is a detailed presentation of results and discussions. Chapter five is the last with a concise summary, conclusions and some recommendations for further studies.