Milly Caller, 22, from Lincoln was arrested in connection with the death of 21-year-old Emma Crossman.
Her body was found at the flat she shared with her boyfriend in January. Police were called to the flat and paramedics tried to revive Crossman, but she was pronounced dead at the scene, according to a Daily Mail report.
A Lincolnshire Police spokesman said: "Following advice from the Crown Prosecution Service, Lincolnshire Police have charged 22 year old Milly Caller from Great Hale with assisting the suicide of another.
"The charge follows her arrest on January 15, 2014 in connection with the death of 21 year old Emma Louise Crossman."
According to the CPS website, "Emma Crossman died on 15 January 2014, having taken her own life using equipment that had allegedly been bought for her by her friend Milly Caller. The CPS has today [15 September 2014] charged Milly Caller with encouraging or assisting suicide."
Rosemary Ainslie, a senior lawyer at the CPS said: "In July 2014 the CPS received a file concerning allegations in relation to the actions of Milly Caller, 22, from Sleaford, in the suicide of Emma Crossman, a 21 year old woman from Lincolnshire.
"Having carefully reviewed the evidence in accordance with the Code for Crown Prosecutors, the CPS has decided that there is sufficient evidence to provide a realistic prospect of conviction, and that a prosecution is in the public interest. Accordingly I have today authorised the police to charge Milly Caller with one charge of encouraging or assisting suicide in that she provided equipment to Emma Crossman with the intent of encouraging or assisting suicide."
Neighbours were shocked to learn of Crossman's death. Sue Price, who lives on the same street, said: "She didn't seem to be depressed or poorly - to hear there's suicide involved just baffles me as she just seemed so lovely, happy and bubbly all the time.
"She lived there with her boyfriend I believe and we used to see her going out with her dad.
"We noticed there were two ambulances outside the house on Wednesday morning but thought it was just something minor.
"We never expected anything like this - it's an absolute tragedy, she was so young."
Adam Deakins who lived opposite the dead woman said: "One of my friends had told me later that she had died and that one of her friends had been arrested. I couldn't believe it."
Assisting a suicide in the UK can carry a sentence of 14 years imprisonment.
In 2009, a Crown Prosecution Service change in policy set out new guidelines which took into consideration public interest in prosecuting suspects arrested over assisting suicide.
The Director of Public Prosecutions, Keir Starmer QC stated: "The policy is now more focused on the motivation of the suspect rather than the characteristics of the victim. The policy does not change the law on assisted suicide. It does not open the door for euthanasia. It does not override the will of Parliament. What it does is to provide a clear framework for prosecutors to decide which cases should proceed to court and which should not.
"Assessing whether a case should go to court is not simply a question of adding up the public interest factors for and against prosecution and seeing which has the greater number. It is not a tick box exercise. Each case has to be considered on its own facts and merits."
Caller is the second person to be charged with the offence since the change in guidelines.
The 22-year-old from Great Hale, Sleaford was bailed pending further investigation, and will appear at Lincoln Magistrates' Court on 16 October.