The 1st Series was originally broadcast between the 30th April and 30th July 1973, consisting of 13 episodes, one 5 part story and two 4 part stories.

Roger Price saw the lead casting as very important, as he wanted talented and attractive actors who would appeal to the young audience, but also be personable and easy to work with during the long hours envisaged in studio or out on location. Nicholas Young was cast as the group's leader, John, while Peter Vaughan Clarke was offered the role of Stephen after Roger saw him in a rendition of Peter Pan with Lulu. Ruth Boswell wanted Lynne Frederick (later the last wife of Peter Sellers) for Carol, the female lead, but following a meeting with her, Paul Bernard felt she was a bit too upper-class and precious for what he had in mind, as he saw the character as being similar to Doctor Who's Jo Grant. They finally settled on Sammie Winmill who was relatively well-known for playing Nurse Crumpton on the popular Doctor at Large situation comedy (also a Thames production). The role of Kenny, the youngest TP, was given to Stephen Salmon after he had been discovered in a drama workshop while theatre actor Philip Gilbert was selected to provide the paternal tones of biotronic computer TIM. 

Making up the team were two Sap friends, a couple of bikers called Ginge (Michael Standing) and Lefty (Derek Crewe) who encounter the Tomorrow People when acting as henchmen for the villainous shape-shifter Jedikiah in the opening adventure. Stephen would be very much the show's hero and focus for the audience while John was something of an authoritarian figure who took his responsibilities for the species' future and welfare very seriously. Young was the only TP to be in every single episode and the actor was able to have some say in the production of later seasons as he was considered as an unofficial producer. Kenny was given very little to do and was often left behind in the Lab (due to being the youngest) while the others went off to have the actual adventures. Filming commenced in March 1973 with location work in Muswell Hill. Production of this first story, 

"The Slaves of Jedikiah" was much troubled, as the crew found they were unfamiliar with the technical demands of a science fiction drama. The first day in studio was disastrous, with virtually no usable material getting made and there was some tension between the cast and Paul Bernard, who was very authoritarian with them. Also, Nicholas Young banged himself hard into a wall while working on the darkened entrance to the Lab, which was being filmed inside the real disused tube station at Wood Lane (closed in the 1940s). Fortunately, he was not badly injured and able to carry on later that day after a recovery break.

Early publicity included a photo session of the cast with the Doctor Who star, Jon Pertwee, to indicate a friendly rivalry between the two shows. Look-in magazine would provide a great deal of coverage of the series and by July would have launched its own comic strip version (which ran on and off in its pages for the next five years). TVTimes also promoted the new show with an article on its first week.

The production procedure was very much standard in the seventies with a limited amount of location work (done on film) followed by a day in studio to record each episode on videotape. Even for the time, some of the special effects of the show were considered sub-par, largely attributable to its small budget.[8] The first season was budgeted at approx £5000 per episode which was roughly half the cost of what the BBC were making Doctor Who for. Most directors on the show would rely heavily on chroma key to get their desired effects, but owing to the rushed time on studio days, the results varied greatly in outcome. To make it even more difficult, studio time was restricted as English law dictated that juvenile actors could only work a certain number of hours in a day.

Season one's recurring villain, Jedikiah, was originally devised to be a long-running foe (like the Master from Doctor Who), but after seeing the poorly-designed robot that was the shape-changer's true form, an unimpressed Price elected not to use the character again until the finale of series three which was planned at that time as the series' finale (the robotic form noticeably fails to appear). Despite these limitations, the series proved popular with its young audience who watched in large numbers, even denting the figures for the popular BBC magazine programme Blue Peter.