Baldock is a town in Hertfordshire, England where the River Ivel rises. It is in the local government district of North Hertfordshire.

Baldock was founded by the Knights Templar (also the name of the town's secondary school) in the 1140s. Indeed, the name Baldock derives from the Old French name for Baghdad: Baldac  which the Templars had hoped to conquer during the crusades, as it was a famous and prosperous city. The popular suggestion that the name is more likely to be derived from "Bald Oak", meaning a dead oak, is a folk etymology unsupported by early forms of the name. The modern layout of the town, and many buildings in the centre, date from the sixteenth century, with the earliest dating from the fourteenth century.

The town grew up where the old Great North Road and the Icknield Way crossed. Despite the construction of the A1(M) motorway in 1970, which bypassed the town (and which was called the Baldock Bypass for some years), it was still a major traffic bottleneck until March 2006, when a new bypass removed the A505 road (old Icknield Way) from the town.

Due to its location, the town was a major staging post between London and the north: many old coaching inns still operate as pubs and hotels, and Baldock has a surprising number of pubs for its size. The high street is very wide, which is a typical feature of medieval market places. Unusually, Baldock has a second market place in White Horse Street. The success of Baldock's market led to the decline of Ashwell as a market town.

The number of pubs becomes less surprising once the adjacent, much larger town of Letchworth Garden City is visited. Letchworth Garden City had no alcohol prior to 1958, and only two pubs plus a hotel bar were present up until the mid 1990s. Its larger population had for many years visited both Baldock and Hitchin for refreshment.

The town has a railway station on the line between London Kings Cross and Cambridge.

There has been human activity on the site well before the modern town was founded. Prehistoric remains on Clothall Common dates back as far as c 3000 BCE. Many Roman remains have been discovered during building work in and around the town, and the core of the Roman settlement is on Walls Field near the Hartsfield Primary School in the town. Earlier Iron Age remains have also been uncovered in the same general location, which may be the earliest town ever to develop in Britain.

A medieval leper colony, on Royston Road, was located during excavations in 2003, having been thought for many years to lie to the south-east of the town on the former Pesthouse Lane (now Clothall Road), the A507.

From 1808 to 1814, Baldock hosted a station in the shutter telegraph chain that connected the Admiralty in London to its naval ships in the port of Great Yarmouth.

An authoritative history of "Baldock's Middle Ages" (ISBN 0-905858-97-2) was compiled by Vivian Crellin, a former headmaster of the Knights Templar School, while local archaeologists Keith Fitzpatrick-Matthews and Gilbert Burleigh published 'Ancient Baldock: the story of an Iron Age and Roman town' in 2007.

In the 1960/70s Baldock was a centre of Laser research at a MOD laboratory called SERL (Services Electronics Research Laboratory). This facility closed in the late 1970s and some projects and staff were transferred to RSRE (Royal Signals & Radar Establishment) near Pershore.

The character of Baldock will no doubt change considerably now that the bypass has opened, removing traffic which has passed from the A1(M  motorway to the A505 towards Royston and Cambridge. The bypass was opened on 16 March 2006.

Baldock was formerly the location of a film processing factory which folded before the company (originally based in Letchworth Garden City) could move in; local folklore has it that it was a silent film studio, but this is not the case. The building was then bought by the Full-Fashioned Hosiery Company from Halifax, later becoming the Kayser Bondor ladies stocking factory (which temporarily produced parachutes during World War II). Its Art Deco facade still stands as the largest Listed Building in the town; it was converted to a Tesco supermarket in the late 1980s. Another notable building in the town is the thirteenth century Baldock Parish Church of St. Mary. Malting and brewing were formerly major industries in the town, but apart from some light industry, today it is mostly a commuter town.

The town has excellent (free) parking facilities. Fewer lorries now pass through the town because of the new bypass. In the past few years, many businesses have shut down in Baldock. Baldock lost its local football side, Baldock Town F.C. in 2001, after nearly a 100 years of existence.