The main conference of Wikimanía 2015 occurred from Friday through Sunday, the 17 to 19 July, at the Hotel Hilton Mexico City Reforma, across from the Alameda Central in the historic center of Mexico City. The education pre-conference and hackathon took place the two days before the main conference.

Iván Martínez, the Wikimanía 2015 coordinator, welcomed the attendees on Friday, then introduced WMF's executive director, Lila Tretikov, who gave the opening plenary address. First, she briefly listed her diverse meetings with WikiArabia, Wikimedia Israel, the Wikimedia Conference 2015, the Wikimedians of the Levant, and Wikimedia Polska, and teleconferencing with the Museo Soumaya editathon. Tretikov compared the growth of Wikimedia to that of cultivating grapes, evolving from seedlings to a cohesive and productive vineyard, in which “together, we are more than the sum of us”. She noted our current challenges: five billion people newly online in this next decade, fast-moving and technology-savvy users, the expanding role of artificial intelligence in knowledge creation, changing knowledge formats, and the opportunities presented by institutions eager to share their knowledge. Tretikov then outlined the strategy consultation that the WMF undertakes with editors across many countries, Wikimedia projects, and languages, and the WMF's desire to partner technology and our communities for innovation. She cited new tools such as editing and adding citations in Visual Editor, Revscore, content translation (including a recommendation algorithm to match translators with missing articles), and new mobile tools (e.g., collections). She noted that the 2015 election of three WMF board members was a team effort in process improvement and editor/voter outreach. Tretikov closed by recommending that we be bold, return to openness and collaboration, focus on what we love and let go of the rest, unite and integrate our work, and embrace diversity.

A pdf from Tretikov 's presentation is here.

Luis von Ahn, co-founder of ReCAPTCHA and duoLingo, spoke on Saturday. He explained that after initially developing this widely used version of the captcha, he grew to feel guilty about occupying users' time solely to distinguish between humans and bots, and that as a result of this ambivalence he had developed a means of presenting a second word in the captcha to aid in translating textual images from scanned books that are unreadable by computers. By pairing an unknown word image with a known one, the captcha server program would use the known word in the image pair to verify the user as human, and would record the response for the unknown word in the image pair until enough human responses were obtained to reliably identify its meaning.

After selling ReCAPTCHA to Google in 2009, he turned his attention to the educational needs of the underprivileged in countries like his birth place of Guatemala, where there is a great need for an inexpensive means to learn English for economic advancement. Thus, duoLingo was born, a free app and web application that required only a smart phone or a computer to use. Honed by applying lessons learned from usability statistics obtained by automated feedback, duoLingo has more than 100 million registered users, and has been extended to a dozen language pairs, although it is largely limited to those of Roman script.

Jimmy Wales delivered the closing remarks. He concentrated on the freedom-of-expression issues that some Wikipedia users and editors are experiencing. He listed two examples and a related philosophical conundrum:

• The initial total blocking of Wikipedia by the Chinese government, followed by a period of filtered blocking of individual pages, then back to a total ban when WMF instituted HTTPS as the web protocol for accessing Wikipedia. He stressed that one of the arguments he would use in his discussion with the Chinese government on the WMF's behalf was that because of the government's blocking actions, the perspective of China within Wikipedia would be represented only by editors outside mainland China
• There are editors who are intimidated and threatened due to their work. In particular, Wales recounted the story of an editor who simply had recorded the results of anti-government protests in Venezuela, including it in articles and uploading photographs to Commons. This editor received death threats and fled the country as result. Venezuela then revoked his passport, leaving him in a legal limbo in which he cannot return to his country or travel elsewhere, and is uncertain of his refugee status where he is.
• The philosophical conundrum that Wales presented was the problem of reliably citing articles about topics that are within countries in which the mass media is controlled by the government. In these cases, the only available references may be those that the government permits.

Wales' announcement of Wikipedian of the year was made in pectore, meaning that he did not reveal the name at this time because doing so has the potential to bring reprisal or harm to the recipient. He also named two honorable mentions, Susanna Mkrtchyan, president of Wikimedia Armenia who has recently been instrumental in promoting the Western Armenian Wikipedia (see also the Signpost coverage), and Satdeep Gill for his contributions and promotion of the Punjabi Wikipedia.