The present book deals with impact of migration in mountain with particular reference to Uttarakhand Mountain which is popularly known as abode of resources. However, in spite of resource abundance, the people of Uttarakhand Mountain region are still economically weak. Agriculture and allied activities being the main occupations engages nearly 80 percent of the total workforce. Agriculture is unable to fulfil the needs of people as it is subsistence in nature and its productivity is also low. The region is also lagging in secondary, tertiary and quaternary activities. Therefore, poor economic conditions of the region force the people to migrate outside the area in search of jobs for better livelihoods and standard of living. They mostly join the military, para military services or settle down mainly in urban centres of North India. The outmigration mainly of youth male has become a common phenomenon since 1900 A.D. With the passage of time, outmigration process has brought numerous changes in socio-economic conditions of the region such as changes in cropping pattern, improved literacy rate, social status and standard of living but notable is the increased workload on women in the absence of male members of the family. Since last few year returned/reverse migrations has also brought many changes. This book is a humble attempt to examine the characteristics of out-migrants and respondents and the impact of out-migration on agricultural land use pattern in Pauri Garhwal district during 1986-87 and in Lachi Gad of Pauri Garhwal during 2015-16 and 2019; characteristics of returned/reverse migrants and active outmigrants in 2020-21; and return/reverse migration during COVID-19. The area is a promising one with serene ambience. The only coordination that is needed to activate is between the authorities and the stakeholders. If this can be channelized the mountain of Uttarakhand can become economically self-sustained and would regulate outmigration too. Another dimension is that if the outmigrants visit the area regularly and keep a continuous link with the native area and many of them return back to native area then it is not that harmful a process. Infact their continuing efforts of sharing knowledge about latest skills and development would boost the economy of the region insitu. They should be in connection with their roots and become instrumental in its holistic development.