Lads' Army (known in later series as Bad Lads' Army, Bad Lads' Army: Officer Class and Bad Lads' Army: Extreme) was a reality game show that constitutes a historically derived social experiment. Shown on ITV, the series is based on the premise of subjecting today's delinquent young men to the conditions of conscripts to British Army National Service of the 1950s to see if this could rehabilitate them.

The programme was derived from an earlier one called simply Lads' Army (a play on Dad's Army) in which a number of volunteers underwent four weeks of basic training for 1950s National Service. Unlike the three sequel series (the ones whose titles began with "Bad"), the original programme's experiment was merely to see if 18- to 24-year-old members of the modern British public could cope with the 1950s training, and how they compared to the public of that period. The success of the original series led to the experiment being repeated with the recruits having committed criminal offences, often given the option to undergo the training by courts as an alternative to serving pending sentences, to explore the proposition that it would be beneficial to reinstate National Service for petty criminals and delinquents as an alternative to more conventional sentences. Series 4 raised the maximum age to 26.

The narrator for the first series was Kevin Whately, then Dennis Waterman took over until the show ended in 2006. Within each series a small number of the recruits have either walked out (after a 24-hour cooling off period), or been ejected. The majority of the remainder claim some benefit from the experience and some have chosen the British Army as a career at the end of it.