Theale (/ˈθiːəl, ˈθiːl/) is a village and civil parish in West Berkshire, England. It is 5 miles (8 km) southwest of Reading and 10 miles (16 km) east of Thatcham. The compact parish is bounded to the south and south-east by the Kennet & Avon Canal (which here incorporates the River Kennet), to the north by a golf course, to the east by the M4 motorway and to the west by the A340 road.

The name is thought to come from the Old English þelu meaning planks. As with the village of Theale in Somerset, this probably refers to planks used to create causeways on marshes or flood plains. A local legend suggests the name Theale refers to the village's coaching inns, and its position as the first staging post on the Bath Road out of Reading – literally calling the village The ale.

The old significance of the position of Theale is that it lay at the junction of two ancient natural routes, one following the Kennet Valley from east to west and another which exploited the valley of the River Pang to run at a low level through the Chiltern Hills from north to south via the Goring Gap. This latter route was taken by a Roman road which ran from Calleva Atrebatum (modern Silchester) north to Dorchester on Thames. Extrapolation of the known alignment from Silchester to near Ufton Nervet indicates a crossing point of the River Kennet just east of Tylemill Bridge. This Roman road has its equivalent in the modern A340 from Theale to Pangbourne.

Roman remains were uncovered during the excavation of the Theale Old Gravel Pit, at the end of St Ives Close, for ten years after 1887. The Kennet Valley route, later the Bath Road, only became important after the foundation of the Anglo-Saxon borough of Reading in the 8th century. The Anglo-Saxons had abandoned Calleva Atrebatum, but the north to south route remained important to them as connecting the royal capital of Winchester with the boroughs of Old Basing near Basingstoke and Wallingford.

From the early Middle Ages to the 19th century, Theale was mostly part of Tilehurst parish. The old parish boundaries around here were complicated, and the village was a chapelry, comprising a western outlier of this large and irregularly shaped parish. The odd parish boundaries by the river indicates that the valley bottom had been converted from swamp forest to flood-meadows or reed-beds for thatching by the start of the second millennium. The portion belonging to Englefield lay between the main river (now the canal) and a branch, called Holy Brook, which left the main course at Sheffield Mill and rejoined it at Reading Abbey. The name was allegedly because the abbey used the brook to power its corn mill and flush its toilets, and so engineered its course to ensure a good head of water.

From before 1241 until the 1800s, Theale, unusually, gave its name to the hundred containing the parishes of Aldermaston, Bradfield, Burghfield, Englefield, Padworth, Purley, Stratfield Mortimer, Sulham, Sulhamstead Bannister, Tidmarsh, Ufton Nervet and Woolhampton. The oddity of this was that the village was not in the hundred, because Tilehurst parish was in the Hundred of Reading. The manor and church of Tilehurst belonged to Reading Abbey in the Middle Ages. However, the chapel at Theale did not but was part of land-holdings in Theale held by the nunnery of Goring Priory by 1291. The nuns also held the neighbouring manor of Sulham, but the chapel had some connection with the church at Englefield.

There is circumstantial evidence of a readjustment of boundaries between Sulham, Englefield and Tilehurst parishes and the possible transfer of Theale in the earlier Middle Ages. In the later Middle Ages, the abbey leased out many of its properties to ensure a cash income at a time when the economy was becoming increasingly cash-driven. The large manor of Tilehurst was subdivided, and a "manor", not actually legally functioning as one, called Beansheaf was in existence by 1390. This was named after a family farming land in the parish in the 13th century. The territory included Theale, but the manor-house was to the east of the present village and the site is now east of the M4, at the north end of Bourne Close. A housing estate in Holybrook parish preserves the name.

Theale saw action in the English Civil War, (1642–51). On 22 September 1643, soon after the First Battle of Newbury, the village was the site of a skirmish between Prince Rupert's Royalist forces and the Earl of Essex's Parliamentarians. Rupert attacked the Earl's forces from the rear as they were returning to London. According to contemporary reports, the Earl's forces – led by Colonel Middleton – held strong; up to 800 Royalist musketeers and 60 horses were killed, and at least eight Parliamentarian units, a minimum of 800 men, were also killed, and were buried on the spot in Deadman's Lane. The Royalist forces retreated, and the Earl left Theale on the morning of 23 September, heading to Reading where his forces recovered from fatigue. Thomas Fairfax marched through Theale on 1 May 1645, en route from Windsor to Salisbury. Evidence for the encounter came to light in 1878, when a sword with the remains of an iron hilt was found near Deadman's Lane. A housing estate in the south-west quadrant of the village has the street names Cavalier Close and Roundhead Road in memory of this skirmish.