The contest was run over four weeks, from 0.00 hrs UTC April 15 to 0.00 hrs May 12 2013. Once this period ended, editors could still submit material they improved during the period. The potential article pool included vital and core articles. Editors are also welcome to improve and nominate an improvement to a broad or important article not on the two lists if they explain why their article should be considered.
The contest now concluded, the judges reviewed the submissions and (after much delay) announced winners at Wikipedia:The Core Contest/Winners in June 2013.