In 2006 the General Assembly Resolution 60/251 (A, C, E, F, R, S) established the Human Rights Council (HRC). This Resolution also called for the HRC to undergo a review of its work and functioning within five years of its initiation.
To this end the HRC set up, through Resolution A/HRC/RES/12/1 - A, C, E, F, R, S at its 12th session in September 2009, an "Open-ended intergovernmental working group on the review of the work and functioning of the Human Rights Council".
This Working Group met in two sessions of five days from 25 - 29 October 2010 and on the 7, 17, 18, 23 and 24 February 2011. On 25 March 2011, the HRC adopted an “Outcome of the review on the work and functioning of the Human Rights Council”. This Outcome contains various new modalities for the HRC and is a supplement to HRC Resolution 5/1.
The summary of UPR modalities brought in for the second cycle are available here.
Ahead of the third UPR cycle the Office of the High Commissioner on Human Rights (OHCHR) made several administrative changes to the mechanism, namely; extending the cycle to five years, publishing new guidelines for States and CSOs, producing matrices, and also deciding to publish all Mid-term Reports.