HIGHLIGHTS Official registration enabled communities to protect forest against encroachment. Registration enabled communities to control and reduce illegal logging. Tenure security is determined by support from law enforcement and forest agencies. Locally-adapted forest institutions were formalised but not altered by registration. Disparities between local and state laws over timber use are tolerated by officials. SUMMARY The formalisation of community forestry through legal registration could enhance the tenure security of local communities, although its effectiveness remains unclear. The issue of whether Thailand's registration programme strengthened the tenure security of community forests and altered their customary forest institutions was investigated. The tenure security and forest management of registered community forests with varying levels of tenure disputes were compared across five different localities. The formalisation process and its effects on tenure security were discussed with representatives from communal forest committees and forest officials. Findings indicated that neither management organisation nor forest rules were altered following registration but remained adapted to local forest uses. Moreover, forest communities were confident in the assurance of their use and management rights. The registration generally enabled communities to prevent further forest encroachment and resolve conflicts if forest officials and police provided support. However, limited financial resources hindered communities to manage and monitor forests effectively.