While possessing near-godlike powers, Q also exhibits a child-like petulance and sense of playfulness. The Enterprise -D made first contact with Q in 2364, when Q detained the ship, enacting a courtroom drama in which Q accused the ship's crew of being "grieviously savage."

On his second visit to the Enterprise -D, Q offered William Riker a gift of Q-like supernatural powers, althought it was not clear if this was a further attempt to study the human species, or merely another exercise in provoking humans to respond for his amusement.

Q later transported the Enterprise -D some7,000 light years beyond Federation space to System J-25, where first contact was made with the powerful and dangerous Borg. In thisepisode we find that Q and Guinan have had a previous relationship. In the file titled 'Dance of Chameleon and Mirror' (which can be found in the Q Database, Stories section), we learn that Guinan was tormented by Q who told her her civilisation was going to end, and that he could save it - but only of she gave herself to him for him do to anything he pleased to her. Using the powers of her race, Guinan saw that Q's statement was in fact true, but she declined his offer in favour of leaving her planet and trying to solve the problem herself, leaving her family on her homeworld. However, whilst she is out searching for evidence of anything that might destory her civilization, the Borg invade her homeworld, assimilating a good number of its population and killing all the rest. After visiting her homeworld and seeing the devastation, Q appeared to her and tormented her for making the wrong choice. Here there was a division of relaities, one in which Guinan did nothing (which is the one depicted in the TV series), and one in which Guinan used her powers to see that Q was going to lose his powers , but would probably get them back again. Guinan twisted reality so that Q wouldn't get his powers back.

Q was banished from the Q Continuum and stripped of his powers in 2366 for having spread chaos through the universe. Q sought refuge in human form on board the Enterprise -D, claiming that Jean-Luc Picard was the nearsest thing he had to a friend. Unfortunately, Q had made many enemies in this universe, and one of these, the Calamarain, attacked the Enterprise -D, attempting to exact revenge on Q. Quick action by Commander Data saved Q from the attacked. Truly surprised by Data's selfless action to save him, Q stole a shuttlecraft in an attempt to save the Enterprise -D crew from further hostile action. This altruistic act was enough to persuade the Continuum to return his powers.

However, in the alternate universe in which Guinan made sure that he wouldn't get his powers back, Captain Picard beamed the shuttle back into the Enterprise. Q was then transported to Starbase 56, where he was supposed to help Federation scientists with his vast knowledge of the universe, in exchange for the Starbase keeping him safe from enemies that he'd made while he was omnipotent. However, he soon became very depressed and very hard to get along with. He attempted suicide several times unsuccesfully, but his next attempt (drinking a bottle of acidic ectching solution) really did endanger his life. However, another member of the Continuum had been keeping an eye on Q, and without Q's knowledge, intervened to save him. The other Q also saved and instructed a female Vulcan named T'Laren to become Q's psychologist, whilst taking him away from Starbase 56, on which he'd made many enemies.

He returned to the Enterprise -D in 2369 to instruct and evaluate Amanda Rogers, whose biological parents were members of the Q Continuum who took human form. After a period of time exploring the Gamma Quadrant, Vash left Q, and returned to the Alpha Quadrant aboard the Starfleet runabout U.S.S. Ganges through the Bajoran wormhole. Q followed Vash to station Deep Space 9 in an attempt to convince her to return, but she once again rebuffed him. He amused himself with the crew of the station, provoking Benjamin Sisko into a 19th-century-style fistfight, and was shocked when Sisko knocked him to the floor.

Later that year, Q once again visited Captain Picard, following a disasterous away mission on which Picard was ambushed by Lenarians. In what Q claimed was the afterlife, Q offered Picard the opportunity to see what his life would have been like had he not made some of the rash choices of his youth. In particular, Picard was given the opportunity to relive the three-day period leading up to his injury at the Bonestall Recreation Facility in 2327. Using the knowledge of what was to come, Picard was able to avoid the fight that cost him his heart. However, Picard discovered that it was partly the brashness of his youth that had made him the man that he was.

Q also paid trips to the Voyager, lost in the Delta Quadrant to all but himself. He was there to apprehend a renegade Q in 2372. Both he and the other Q had Captain Janeway mediate a hearing where the renegade Q argued he was tired of eternal existence and wanted to turn into mortals and end his life. Q tried to lobby for Janeway's support by offering to return the Voyager to the Alpha Quadrant if she sided with him, but Janeway let her conscience decide and agreed with the argument of the renegade Q. Q courting Captain Janeway's favor in 'The Q and the Grey' The renegade Q was named "Quinn" by the crew and when he changed into mortal flesh, Q assisted in his suicide. It was then that Q understood his wish.