Construcciones y Auxiliar de Ferrocarriles (Grupo CAF, literally "Construction and Other Railway Services") is a Spanish publicly listed company which manufactures railway vehicles and equipment and buses through its Solaris Bus & Coach subsidiary. It is based in Beasain, Basque Autonomous Community, Spain. Equipment manufactured by Grupo CAF includes light rail vehicles, rapid transit trains, railroad cars and locomotives, as well as variable gauge axles that can be fitted on any[citation needed] existing truck or bogie.
 Over the 20 years from the early 1990s, CAF benefited from the rail investment boom in its home market in Spain to become a world player with a broad technical capability, able to manufacture almost any type of rail vehicle. CAF has supplied railway rolling stock to a number of major urban transit operators around Europe, the US, South America, East Asia, India, Australia and North Africa.
 CAF was an acronym for the earlier name of Compañía Auxiliar de Ferrocarriles, as well as for Construcciones y Auxiliar de Feres.
 In 1860, Domingo Goitia, Martín Usabiaga and José Francisco Arana established this company, whose main activity was puddling furnaces and cylinder rolling.
 In 1892, Francisco de Goitia (Domingo Goitia's son and heir) joined the Marquess of Urquijo to set up La Maquinista Guipuzcoana, whose main activity was the operation of machinery and the forging and construction of railway rolling stock.
 In 1898, it set up its plant in Beasain, Gipuzkoa. In 1905 it changed its name to Fábrica de Vagones de Beasain (FVB).
 Compañía Auxiliar de Ferrocarriles (CAF) was founded in 1917, specializing in freight car production and with a total of 1,600 employees.
 In 1940, the Irun factory was set up, following the expansion of activity after the Spanish Civil War (CAF took part in reconstructing the Spanish rail fleet).
 In 1954, CAF took over Material Móvil y Construcciones (MMC) from Zaragoza (Aragon), a company with extensive experience in manufacturing long-distance and subway trains.
 Since 1958, the company has modernized and enlarged its Beasain plant and expanded its activity to include all kinds of rolling stock. In line with this, in 1969 CAF created its Research and Development Unit, which increased the company's competitiveness and intensified the focus on in-house technology.
 In 1971, the existing Compañía Auxiliar de Ferrocarriles (CAF) merged with Material Móvil y Construcciones (MMC) and the company adopted its current name Construcciones y Auxiliar de Ferrocarriles.
 Since the early 1990s, CAF has also been active internationally. In the early 2000s, CAF supplied high-speed trains to the Spanish RENFE and in 2005, high-speed trains were exported for the first time (to Turkey). 
 In 2018, CAF took over the Polish bus manufacturer Solaris. The company also acquired the Talent 3 platform from competitor Bombardier Transportation in 2022, as well as the Coradia Polyvalent platform and the plant in Reichshoffen from train manufacturer Alstom. This was a condition imposed by the European Commission's competition authority for the approval of the 2021 takeover of Bombardier Transportation by Alstom. 
 CAF U.S.A., a wholly owned subsidiary of CAF, was incorporated in 1998 and is based in Elmira, New York.  It manufactures rolling stock for the North American market at a plant in Elmira that the company acquired from ADtranz in 2000. The company from Beasain continued its expansion during the third millennium.
 On 24 May 2019, it announced the acquisition of the Swedish company Euromaint at a cost of circa €80 million, following other international contracts to supply Flemish and English railway and underground networks in 2017.
 CAF Rolling Stock U.K. Ltd. is the CAF subsidiary in the United Kingdom. Its factory is based at Celtic Springs Business Park, at Llanwern steelworks near Newport, Wales as a result of an agreement made between CAF and the Welsh Government. The Newport factory has built stock for Transport for Wales, Arriva Rail North, the Docklands Light Railway, and potentially High Speed 2 if CAF win the bid process. They also donated £150,000 to the Conservative Party.
 CAF Signalling was fined in 2021 with 1.7 million euros by the Spanish commission on markets and competition because of its participation in a cartel with other 7 international companies which colluded in tenders over Spanish rail infrastructure.
 In April 2014, two carriages of an Urbos 3 tram in Belgrade separated during passenger service, due to the cracking of screws connecting the cars. Half of the Belgrade tramway's CAF fleet were found to have been affected by similar cracking of screws in the two weeks prior to the incident.
 In March 2016, 19 British Rail Class 332 units were taken out of service after a crack was discovered in the underframe of one unit during routine maintenance.
 In December 2017, the Besançon Tramway in Besançon, France discovered cracks in their Urbos 3s vehicles around the bogie box area of the bodies, which in December 2020 CAF paid for remedial work to be performed with each unit affected requiring one month downtime for the work to be completed.
 In April 2021, 22 British Rail Class 195 Civity units were temporarily removed from service after routine maintenance revealed a yaw damper bracket had detached from the body of unit 195121.
 On June 11, 2021, West Midlands Metro (operating between Birmingham and Wolverhampton, England) were forced to suspend their services due to cracks being discovered in the bogie box areas of their Urbos 3s vehicles, with ongoing investigations continuing to identify any other issues relating to the cracks and to find options for remedial works to be performed. Full service only began once more in February 2022.
 On June 24, 2021, Flytoget were forced to withdraw their entire CAF Oaris fleet after 19 days of service due to the discovery of cracks in the chassis. They remain out of service as of September 2022, with plans to reinstate them by the end of the year. In the meantime, CAF has paid an unknown amount to Flytoget in compensation.
 Following on from these instances, in November 2021 the New South Wales transport minister Rob Stokes announced that the Sydney L1 Dulwich Hill Line would be decommissioned for up to 18 months, due to serious design flaws in all 12 of the CAF Urbos 3s tram sets that were running on the line. Stokes stated that the flaws (in the bogie boxes) were likely to be far broader in scope than those identified in Sydney due to the thousands of the same tram type operated around the world.
 In March 2022, the West Midlands Metro was again forced to suspend its services due to the discovery of more cracks, this time on the bodywork of the trams.
 On February 17, 2023, the Department of Transportation of the Philippines revealed that nearly 80 of the new light rail vehicles for Manila's LRT Line 1 cannot be used due to water leaks in the cars.
 In February 2023, CAF revealed that the 2020 project for 31 trains for the FEVE narrow-gauge lines in the northern regions of Cantabria and Asturias, Spain, asked for a carriage width that would not fit through the existing 19th-century tunnels. The change in specifications will delay the established delivery date of October 2024 by two years to 2026.
 In July 2023, body cracks were discovered in four British Rail Mark 5A "Nova 3" carriage sets, leading to daily inspections of all sets and the temporary withdrawal of five sets from service. That August, the operator TransPennine Express confirmed its intention to cease usage of all sets from the December 2023 timetable change.
 During the 2019 United Kingdom general election, CAF Rail UK Limited made a donation of £50,000 to the Conservative Party.
  In 2019, it entered into litigation that affects its corporate image. Participating in a consortium, JNET, together with the Israeli company Shapir Engineering and Industry, has won a tender promoted by the Israeli Ministry of Transport and Road Safety to supply railway equipment, in addition to building, extending and operating light rail lines from Jerusalem to nearby settlements in disputed territories, in violation of the Fourth Geneva Convention. In turn, Shapir is on the list of companies that benefit from the occupation in the Occupied Palestinian Territories, as denounced by the United Nations Human Rights Council.
 For FEVE, now part of Renfe Operadora:
 For Euskotren:
 For Serveis Ferroviaris de Mallorca:
 For other operators:
 For Madrid:
 For Barcelona:
 For Helsinki:
 For Bucharest:
 For Amsterdam:
 For Brussels:
 CAF Rolling Stock U.K. Ltd announced in 2017 its UK factory location was selected as Celtic Business Park at Llanwern steelworks in Newport, Wales. It has at least five confirmed UK projects from 2019 onwards and would have been the construction site for their unsuccessful bid to deliver stock for High Speed 2. The site was funded with support from the Welsh Government Inward Investment Programme.