The arrival of a population on a territory brings a potential source of additional work that overall allows the host country to increase its growth as shown by Chojnicki and Ragot (2012) in their study. However, the France has the particularity of being present on different continents and thus holding territories with great disparity. Through this article, we want to focus on immigration in French Guiana, looking for explanatory factors for the reasons for immigration to this territory. At the same time, we are asked about the contributions of this immigration to know if it represents an asset or a constraint for the development of the territory. The answer is obviously not binary, which gives more interest and complexity to the question. Thus, we were able to carry out a first theoretical analysis in order to grasp the most relevant elements to be studied in order to set up the empirical analysis. Then, we chose a Probit model that we then confronted with the Hosmer-Lemeshow test. The theoretical analysis allowed us to highlight various elements of informal integration (housing, working conditions) that also promote a form of precariousness. Empirical analysis, she rather highlighted the correlated factors that support this immigration rate. Finally, we observed the case of the Hmong population settled in French Guiana for several decades, which represent a relatively successful example of immigration with a positive economic impact.