An important part of practising sustainable forest management is the reforestation of forest areas that are damaged by fires or by other destructive activities, such as logging or mining. A wide variety of trees are used for this purpose. However, since individual plant species often have specific environmental requirements, some species are obviously more suitable for reforestation than others. Consequently, the planting of seedlings of a certain species in a habitat that is not suitable for this particular taxon decreases the success of reforestation remarkably. This requires much emphasis on the correct identification of seedlings. Identifying seedlings is often very difficult, as they may differ conspicuously in their general morphology from the adult stages and many distinguishing characters are often not yet present. This manual provides: - Descriptions and identification keys for seedlings of 113 taxa of secondary forest trees (representing 40 plant families); - Drawings and colour photographs of almost all species; - An extensive glossary. These data are presented as a user-friendly bilingual field guide (English/Bahasa-Indonesia) and will enable (local) people without a thorough botanical background to identify many of the secondary forest tree species of East Kalimantan.