In psychology, the Asch conformity experiments or the Asch Paradigm were a series of laboratory experiments directed by Solomon Asch in the 1950s that demonstrated the degree to which an individual's own opinions are influenced by those of a majority group.

In 1951, Solomon Asch of Swarthmore College conducted one of his first conformity laboratory experiments, laying the foundation for his remaining conformity studies. The conformity experiment was published on two occasions.

Male college students participated in a simple "perceptual" task. In reality, all but one of the participants were "confederates" (i.e., actors), and the true focus of the study was about how the remaining student (i.e., the real participant) would react to the confederates' behavior.
Each participant was placed in a room with seven "confederates". Confederates knew the true aim of the experiment, but were introduced as participants to the "real" participant. Participants were shown a card with a line on it, followed by a card with three lines on it (lines labeled A, B, and C, respectively). Participants were then asked to say aloud which line (i.e., A, B, or C) matched the line on the first card in length. Each line question was called a "trial". Prior to the experiment, all confederates were given specific instructions on how they should respond to each trial. Specifically, they were told to unanimously give the correct response or unanimously give the incorrect response. The group sat in a manner so that the real participant was always the last to respond (i.e., the real participant sat towards the end of a table). For the first two trials, the participant would feel at ease in the experiment, as he and the confederates gave the obvious, correct answer. On the third trial, the confederates would all give the same wrong answer, placing the participant in a dilemma. There were 18 trials in total and the confederates answered incorrectly for 12 of them. These 12 were known as the "critical trials". The aim was to see whether the real participant would change his answer and respond in the same way as the confederates, despite it being the wrong answer. Once the experiment was completed, the "real" participant was individually interviewed; towards the end of the interview, the participant was debriefed about the true purpose of the study. Participants' responses to interview questions were a valuable component of Asch's study because it gave him a glimpse of the psychological aspects of the experimental situation. It also provided Asch with information about individual differences among participants.

Solomon Asch's experiment also had a control condition where there were no confederates, only a "real participant". This meant that one participant answered to all 18 trials without the group of confederates present and with only the experimenter in the room. In total, there were 50 "real" participants that took part in the experimental condition and 37 participants in the control condition.