The goal of the research is to assess structural dynamics of customary land tenure in Imeko communities as a result of emergence regarding the operations of PT ANJ-AgriPapua and PerumPerhutani in Sorong Selatan Regency. The objectives are as follows: (1) to identify and map the structure of customatyland tenure rightsover the Natural Sago Forest (NSF) in Imekko; (2) to identify and mapstuructural dynamics of customary land tenure on the NSF in relation with the emergence of PT ANJ-Agri Papua and PerumPerhutani in Imekko. The research reveals that the customary land tenure exists under communal and collective ownership with regard to <i>keret/fam</i> (family names). Local communities are entitled with rights to access, collect forest products, use, control, manage, transfer and release, reclaim, and own their land. Individuals who do not have rights over the customary land are able to acquire ownership after obtaining permission with or without compensation on the line. In the case of Dusun Sagu, ownership belongs to family groups (member of nuclear family). Inheritanceon the NSF and Dusun Sagu are passed downtosons, or to the <i>keret/fam</i>, heirsof the family who cultivated the land. Moreover, the research finds that the structures of customary land tenure among Imekko communities are changing due to the emergence of PT ANJ-Agri Papua and Perum Perhutani in the area. From the eight rights that have been practiced for generations, only three rights remain: rights for limited access, use, and collecting forest products in the concession area of the factories. The community groups are supported to utilize these rights in order to meet their basics needs as well as and to generate income through forest utilization.