Standard Lao, the official language in the Lao PDR, is spoken in and around the capital Vientiane. Lexicon, vowels and especially tone inventories of the many Lao dialects in the nation differ tremendously. A new orthography to replace the traditional Pali-based orthography which was hard to teach and learn was established during the Lao language reform in 1975. This study investigates the grapheme-phoneme correspondences of Lao orthography and its applicability to other languages in the multilingual nation. After a short introduction to the Lao language and the linguistic situation in the country, the Lao phoneme inventory and a description of the nature and historical development of Lao script are presented, including some taxonomic considerations discussing the segmental, suprasegmental and syllabic features of this script. This is followed by a linguistic evaluation of the orthography and a summary in the light of how to apply Lao script to other languages spoken in the country. Three minority orthographies based on Lao script illustrate that the almost entirely direct phonemic correspondences, consistency in the formation of multigraphs, the rich grapheme inventory and the both segmental and syllabic characteristics of this semi-alphabetic script support a direct application to other, even unrelated languages with contrastive suprasegmental features like tone or voice quality. No orthography testing or studies on literacy acquisition have been done on these or any other Lao-script based minority scripts yet, so that firm recommendations regarding the creation of new Lao-script based orthographies cannot be given.