The Lepcha script is also called the Róng script - Lepcha people call themselves Róngkup, children of the Róng. It is used for writing the Lepcha language, a Tibeto-Burman language spoken by about 52,800 people in India, Nepal and Bhutan. The script is derived from Tibetan writing, probably motivated by Buddhist missionary activity in the 1700s. Early manuscripts were written in vertical columns but later and current texts are written horizontally. Many letters, when rotated back to their previous vertical position, closely resemble their Tibetan counterparts.

The script comprises twenty-nine basic CV letters, called 'mother letters', where V is [a], and nine vowel diacritics, called 'child letters', which are used to represent post-consonantal vowels other than [a]. There are also three letters which have been added since the late 1990s for representing the retroflex consonants [ʈ], [ʈh], [ɖ]; these letters are used only in Sikkim, India. Elsewhere these sounds are written with the kra, hra and gra ligatures modified by nukta - a dot written below the letter. Any consonant can be used at the start of a syllable, and any vowel at the end, but only [k], [t], [n], [p], [m], [r], [l] can be used at the end. Final forms exist for representing these seven sounds syllable-finally; these are diacritics written above the base letter. Syllable-initial vowels are written with a vowel-carrier which represents [a] when unmarked, or any of the other nine vowels when marked with the appropriate diacritic.

Three consonants can be used medially, r, y and l. Clusters containing medial [r] or [y] are written with special ligating forms which attach to the base letter. Ligating forms of r and y can also combine to produce a post-consonantal -rya ligature. Clusters with medial [l] are written using a set of seven letters representing [kla], [gla], [pla], [fla], [bla], [mla], [hla]. These letters cannot be decomposed into individual C+l parts.

Two other non-alphabetic signs are used as well as nukta. Letters modified with nukta are called nuktated. The sign called nyindo is written to the left of the mother letter to indicate a final velar nasal when no specific vowel is written. So s + nyindo = [saŋ]. Where a different vowel is intended, the lakang sign is used together with the appropriate vowel diacritic.

Lepcha writing uses script-specific digits from 0-9, and, when copying traditional texts, five punctuation marks. In modern texts, Latin punctuation is normally used, together with the Tibetan tsheg symbol.