Pre-debut
In 2013, Pledis Entertainment began the regular live broadcasting of a program called 17 TV on the online streaming platform UStream. During various broadcasts, fans were invited to watch Seventeen as they trained in their practice room. The show had different 'seasons' in which they unveiled their trainees to the public, some ending in their own 'Like Seventeen Concerts'.
Big Debut Plan
On April 19, 2015, Pledis Entertainment began releasing teasers for Seventeen's first reality show, Seventeen Project: Big Debut Plan on a major broadcasting channel, MBC Entertainment. The first episode premiered on May 2, 2015 and the show ended on May 26 with a live debut showcase with labelmates Lizzy and Raina from After School as MCs.
2015: Debut and "Boys Be"
Seventeen debuted on May 26 with a live showcase, with labelmates Lizzy and Raina from After School as MCs. Seventeen is the first Korean pop male group to debut with a 1-hour live showcase on a major broadcasting channel.
Three days after debut, the extended play 17 Carat was digitally released along with the music video for their title track, called "Adore U" (아낀다). It was revealed that the extended play was mostly composed and produced by the members themselves. The physical album was released on June 2. Despite the group coming from a relatively small company, the album ranked ninth on the Billboard World Albums chart a week after its release and peaked at eighth, staying on the chart for a total of eleven weeks. The album debuted at number 8 on the Gaon Album Chart and has peaked at number 4. The album also peaked at number three in the domestic albums category.
On August 31, Seventeen began releasing teasers for their second mini album Boys Be on their official social media, of which the tracklist and two different album versions were revealed on September 3. This second extended play was released on September 10 together with the music video for their title track "Mansae" (만세). Again it was revealed that the members co-produced, composed and wrote the album themselves. The pre-order sales for Boys Be surpassed 30,000 album copies before it was released. The album debuted at number 2 on the Gaon Chart and at number 1 Worldwide.
