Newbridge, officially known by its Irish name Droichead Nua (pronounced [ˈd̪ˠɾˠɛçəd̪ˠ ˈn̪ˠuə]), is a town in County Kildare, Ireland. While the nearby Great Connell Priory was founded in the 13th century, the town itself formed from the 18th century onwards, and grew rapidly alongside a military barracks which opened in the early 19th century. Taking on the name Newbridge (An Droichead Nua) in the 20th century, the town expanded to support the local catchment, and also as a commuter town for Dublin. Doubling in population during the 20 years between 1991 and 2011, its population of 24,366 in 2022 makes it the second largest town in Kildare and the sixteenth-largest in Ireland.

The Irish language name of the town is the official name, "An Droichead Nua", meaning simply "The New Bridge" and was introduced in the 1930s. Noble and Keenan's map of Kildare 1752, drawn before the town was started, marks 'The New Bridge' in the vicinity of 'Old Connel'. A number of other places marked on this map, including Ballymany and Morristown Biller, are represented in the names of modern housing estates and streets.^{[citation needed]}

Settlement in the area dates from the 13th century (with the foundation of Great Connell Abbey), and the current town is made up of six ancient civil parishes along with portions of others. The parishes are Ballymany, Great Connell, Killashee, Morristown Biller, Old Connell, and Carnalway. Great Connell Priory was an important Priory, founded in 1202 by the Augustinian Canons.

The earliest known mention of Newbridge was by traveller and bookseller John Dunton in 1698, though he does not refer to any settlement other than at Ballymany. A mass house (Roman Catholic Chapel) was built beside the bridge about 1730 and an inn, called New Bridge Inn, was in existence in 1750. The first bridge was destroyed by floods in 1789, and William Chapman, an engineer on the Grand Canal extension to Naas, was employed to rebuild it the following year. He moved the site from the 'Watering Gates' to its present location and redirected the high road from Buckley's Cross (roundabout at Pfizer) to the new bridge, and continuing as what is today Main Street and Edward Street to the turnpike at Gandogue Lane (behind the modern Credit Union building). The old high road continued in use to serve the village and mass house, which was taken down in 1852 upon the opening of the new church (St Conleth's).

The origin of the modern town lies in the establishment of Cavalry Barracks (1815–1819) on land purchased from three local landlords: Eyre Powell of Great Connell, Ponsonby Moore of Moorefield and William Hannon of Kilbelin. This barracks originally extended from the River Liffey to Cutlery Road, and from Main Street to Military Road, however little of the barracks remains today except the old walls and gateways which can be found on the Athgarvan Road, and to a lesser degree on Cutlery Road. The "Watering Gates" located at the entrance to the Town Park was also constructed as part of the original Barrack building (and as the name suggests, this "gate" was used to facilitate access to the river for the horses from the barracks). At the same time, Eyre Powell gave land north of the new high road for building houses and shops to serve the new Barracks. Main Street took shape at the same time as the Barracks were being built. From 1819 various Cavalry Regiments were stationed at Newbridge and brought much business to the town.

Newbridge expanded rapidly after the Curragh Camp was established in 1855. Eyre Street (named after the local landlord Eyre Powell) and Edward Street (named after Prince Edward, later King Edward VII, who was stationed on the Curragh at the time) were built between 1855 and 1870. The new railway opened in 1846, and churches were built at Rosberry Common (1819 – St. Eustace', Dominican), at Moorefield (1828 – St Patrick's, Church of Ireland) and at Chapel Lane (1852 – St Conleth's, Roman Catholic) to cater for the increasing population. A National School was opened on the Railway Road in 1842 (now the Parish Office) and a boarding school at the Dominican Friary in 1852. The town continued to prosper until the withdrawal of the cavalry in May 1922 on the establishment of the Free State. It went into a period of decline thereafter, but since the 1960s has seen considerable growth and has become a shopping catchment and commuter town.

Newbridge Town Hall was commissioned as a chapel-cum-school for the local barracks, completed in 1860 and converted for municipal use in 1927.

The town is located on the banks of the River Liffey. Upriver are towns such as Athgarvan, Kilcullen and Blessington, while downriver are the towns of Caragh, Clane and Celbridge.