WARREN, C.J., Opinion of the Court MR. CHIEF JUSTICE WARREN delivered the opinion of the Court. This case presents serious questions concerning the role of the Fourth Amendment in the confrontation on the street between the citizen and the policeman investigating suspicious circumstances. Petitioner Terry was convicted of carrying a concealed weapon and sentenced to the statutorily prescribed term of one to three years in the penitentiary. [n1] Following [p*5] the denial of a pretrial motion to suppress, the prosecution introduced in evidence two revolvers and a number of bullets seized from Terry and a codefendant, Richard Chilton, [n2] by Cleveland Police Detective Martin McFadden. At the hearing on the motion to suppress this evidence, Officer McFadden testified that, while he was patrolling in plain clothes in downtown Cleveland at approximately 2:30 in the afternoon of October 31, 1963, his attention was attracted by two men, Chilton and Terry, standing on the corner of Huron Road and Euclid Avenue. He had never seen the two men before, and he was unable to say precisely what first drew his eye to them. However, he testified that he had been a policeman for 39 years and a detective for 35, and that he had been assigned to patrol this vicinity of downtown Cleveland for shoplifters and pickpockets for 30 years. He explained that he had developed routine habits of observation over the years, and that he would "stand and watch people or walk and watch people at many intervals of the day." He added: "Now, in this case, when I looked over, they didn't look right to me at the time." His interest aroused, Officer McFadden took up a post of observation in the entrance to a store 300 to 400 feet [p*6] away from the two men. "I get more purpose to watch them when I seen their movements," he testified. He saw one of the men leave the other one and walk southwest on Huron Road, past some stores. The man paused for a moment and looked in a store window, then walked on a short distance, turned around and walked back toward the corner, pausing once again to look in the same store window. He rejoined his companion at the corner, and the two conferred briefly. Then the second man went through the same series of motions, strolling down Huron Road, looking in the same window, walking on a short distance, turning back, peering in the store window again, and returning to confer with the first man at the corner. The two men repeated this ritual alternately between five and six times apiece -- in all, roughly a dozen trips. At one point, while the two were standing together on the corner, a third man approached them and engaged them briefly in conversation. This man then left the two others and walked west on Euclid Avenue. Chilton and Terry resumed their measured pacing, peering, and conferring. After this had gone on for 10 to 12 minutes, the two men walked off together, heading west on Euclid Avenue, following the path taken earlier by the third man. By this time, Officer McFadden had become thoroughly suspicious. He testified that, after observing their elaborately casual and oft-repeated reconnaissance of the store window on Huron Road, he suspected the two men of "casing a job, a stick-up," and that he considered it his duty as a police officer to investigate further. He added that he feared "they may have a gun." Thus, Officer McFadden followed Chilton and Terry and saw them stop in front of Zucker's store to talk to the same man who had conferred with them earlier on the street corner. Deciding that the situation was ripe for direct action, Officer McFadden approached the three men, identified [p*7] himself as a police officer and asked for their names. At this point, his knowledge was confined to what he had observed. He was not acquainted with any of the three men by name or by sight, and he had received no information concerning them from any other source. When the men "mumbled something" in response to his inquiries, Officer McFadden grabbed petitioner Terry, spun him around so that they were facing the other two, with Terry between McFadden and the others, and patted down the outside of his clothing. In the left breast pocket of Terry's overcoat, Officer McFadden felt a pistol. He reached inside the overcoat pocket, but was unable to remove the gun. At this point, keeping Terry between himself and the others, the officer ordered all three men to enter Zucker's store. As they went in, he removed Terry's overcoat completely, removed a .38 caliber revolver from the pocket and ordered all three men to face the wall with their hands raised. Officer McFadden proceeded to pat down the outer clothing of Chilton and the third man, Katz. He discovered another revolver in the outer pocket of Chilton's overcoat, but no weapons were found on Katz. The officer testified that he only patted the men down to see whether they had weapons, and that he did not put his hands beneath the outer garments of either Terry or Chilton until he felt their guns. So far as appears from the record, he never placed his hands beneath Katz' outer garments. Officer McFadden seized Chilton's gun, asked the proprietor of the store to call a police wagon, and took all three men to the station, where Chilton and Terry were formally charged with carrying concealed weapons. On the motion to suppress the guns, the prosecution took the position that they had been seized following a search incident to a lawful arrest. The trial court rejected this theory, stating that it "would be stretching the facts beyond reasonable comprehension" to find that Officer [p*8] McFadden had had probable cause to arrest the men before he patted them down for weapons. However, the court denied the defendants' motion on the ground that Officer McFadden, on the basis of his experience, had reasonable cause to believe . . . that the defendants were conducting themselves suspiciously, and some interrogation should be made of their action. Purely for his own protection, the court held, the officer had the right to pat down the outer clothing of these men, who he had reasonable cause to believe might be armed. The court distinguished between an investigatory "stop" and an arrest, and between a "frisk" of the outer clothing for weapons and a full-blown search for evidence of crime. The frisk, it held, was essential to the proper performance of the officer's investigatory duties, for, without it, "the answer to the police officer may be a bullet, and a loaded pistol discovered during the frisk is admissible." After the court denied their motion to suppress, Chilton and Terry waived jury trial and pleaded not guilty. The court adjudged them guilty, and the Court of Appeals for the Eighth Judicial District, Cuyahoga County, affirmed. State v. Terry, 5 Ohio App.2d 122, 214 N.E.2d 114 (1966). The Supreme Court of Ohio dismissed their appeal on the ground that no "substantial constitutional question" was involved. We granted certiorari, 387 U.S. 929 (1967), to determine whether the admission of the revolvers in evidence violated petitioner's rights under the Fourth Amendment, made applicable to the States by the Fourteenth. Mapp v. Ohio, 367 U.S. 643 (1961). We affirm the conviction.