Shellie Callaghan, 16, from Newtongrange, Midlothian, was rushed to hospital on Saturday after she fell ill at a party in her hometown.
Police issued a drugs warning just hours after her death, but said inquiries were at an early stage.
Last night, a vigil was held for the youngster in Newtongrange Park, Midlothian.
Groups of youngsters lit candles in memory of Shellie in the local church hall, and stood in silence while they recalled the happy times they’d spent with her.
The 16-year-old has been described by her friends on social media as a “beautiful” and “popular” girl. Many have been using the hashtag #smileforshellie to pay tribute on Twitter.
Tasha Moffat tweeted: “No-one deserves this no matter what anyone says. “Fly high beautiful. Thoughts are with her close friends and family #smileforshellie”
Thea McDonald wrote: “Absolutely lost for words. You were an absolute gem, you made us all laugh so much and I will never laugh that much again. #smileforshellie”
Shellie’s Facebook page has also been flooded with heartfelt messages. Dozens of friends posted love hearts under her previous profile photographs on Facebook.
One friend wrote: “The memories I have with you will never be replaced.
”It is understood Shellie had been at a party with her friends when she fell ill.
Just hours after her death, police said they were investigating one line of enquiry that suggested she may have had access to ecstasy-type tablets.
They issued a warning for anyone who has taken the tablets, known as red bugatti veyron and purple ninja turtle, to seek “immediate attention”.
In a statement, the force said: “Police Scotland’s message is clear. There is no safe illegal drug and no safe way to take illegal drugs.”
Yesterday, police said that Shellie’s family had asked for privacy while they come to terms with their “tragic loss”.
Chief Inspector Matt Paden said: “As inquiries continue into the full circumstances surrounding the tragic death of Shellie Callaghan, officers from the inquiry team are providing support to her family.
“Officers will also be continuing high visibility patrols over the weekend and the days ahead to provide support and advice to the local community.”