Poshī-daśamī (Poshi dasham) is the Jain festival that commemorates the birth of Lord Parshvanath. It is observed as Poṣa-daśamī, often called Parshvanātha-jayantī.

When it occurs:

• It falls on the 9th, 10th, and 11th days of the dark fortnight (vadī) of the month Poṣa (Pauṣa) in North Indian calendars, or on the corresponding days in Gujarati/Mārgaśīrṣa-based calendars. In the Western calendar, Poṣa-daśamī typically happens in late December to early January, though the exact dates shift each year due to regional lunar calendars. ( jainpedia.org)

Key points:

• It is observed by all Jain sects, with practices like fasting, worship, and listening to sermons about Parshvanath.
• The celebration centers on Parshvanath’s birth and aims to inspire peace, purification, and spiritual progress.

Tradition across Digambara/Shvetāmbara:

• Both traditions honour Poṣa-daśamī as Parshvanath-jayantī, but calendar calculations can differ by region (north Indian vs. Gujarati calendars), so the exact tithi may vary by community. The essential spirit—reverence for Parshvanath and spiritual vows—remains the same. ( jainpedia.org)

If you’d like, tell me your region or the year, and I can give the exact Gregorian dates for Poṣa-daśamī in that year.