The subject of migration has gained great currency over the past few decades, with more and more focus being given to the socio-economic dimensions and the resultant effects of this complex phenomenon. However, migration data collection is one area of the subject which has been lacking, especially with regard to large-scale data on migration. Large-scale data collection plays an important role in understanding phenomena and, subsequently, policy interventions. This is important especially in India, which is a hub of not only emigration but also internal migration. However, India does provide some examples of large-scale migration data collection. This chapter takes a look at how large-scale migration data has been collected and the way forward, especially in the Indian context. The chapter begins with an overview of the migration statistics and collection of migration databases around the world. Later, it focuses on the migration surveys conducted in India, and highlights the eight rounds of the Kerala Migration Survey (KMS). The twenty-year experience of the various rounds of the KMS is touched upon, highlighting its evolution with regard to the type of data it has collected over the years. The adoption of the KMS model of migration surveys in a few states – namely Goa, Gujarat, Punjab and Tamil Nadu – is further discussed. The chapter concludes with the conceptualisation of the India Migration Survey based on the experience of the Kerala Migration Survey model.