|Centuries:||7th century – 8th century – 9th century|
|Decades:||710s 720s 730s – 740s – 750s 760s 770s|
|Years:||739 740 741 – 742 – 743 744 745|
|742 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1495|
|Bahá'í calendar||-1102 – -1101|
|English Regnal year||N/A|
|Chinese calendar||辛巳年 (Metal Snake)
3438 or 3378
— to —
壬午年 (Water Horse)
3439 or 3379
|- Vikram Samvat||798–799|
|- Shaka Samvat||664–665|
|- Kali Yuga||3843–3844|
|Igbo calendar||-258 – -257|
|Japanese calendar||Tenpyō 14
|Minguo calendar||1170 before ROC
|Thai solar calendar||1285|
|Wikimedia Commons has media related to 742.|
Year 742 (DCCXLII) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. The denomination 742 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Chinese poet Li Po is presented before the emperor and given a position in the Imperial court (approximate date).
- Artabasdus is Byzantine Emperor until the capital is stormed by Constantine V, who regains control and resumes the suppression of image-worship.
- Emperor Xuanzong of Tang begins to favor Taoism over Buddhism, adopting the new reign title Tianbao ('Heavenly Treasures') to indicate his divine mandate.
- For the municipal census of the Chinese capital city Chang'an and its metropolitan area of Jingzhou Fu (including small towns in the vicinity), the New Book of Tang records that in this year there are 362,921 registered families with 1,960,188 persons.
- In China, f a million due to Emperor Xuanzong's earlier reforms.
- China's population reaches approximately 50 million.
- Liutprand, King of the Lombards, absorbs the independent duchies of Spoleto and Benevento into his kingdom.
- The Arab troops of the caliphate suppress the Berber rebellion in the region of Mértola (present-days Portugal).
- Saint Sturm establishes the abbey of Fulda (or 744?).
- After a forty-year vacancy, Stephen IV becomes Orthodox Patriarch of Antioch at the suggestion of Umayyad caliph Hisham ibn Abd al-Malik.
- Chrodegang, chancellor of Charles Martel, is appointed bishop of Metz and embarks on a reorganisation of the Frankish church.
- The Holy Face of Lucca is transferred to Lucca from Luni (traditional date).
- Serrão, Joel; de Oliviera Marques, A. H. (1993). "O Portugal Islâmico". Hova Historia de Portugal. Portugal das Invasões Germânicas à Reconquista. Lisbon: Editorial Presença. p. 123.