The country's biggest A-level and GCSE provider has bought a teaching resources company, announcing a plan to diversify and become "more than just an exam board".
Exams regulator Ofqual says it is looking into the acquisition of Teachit by AQA, which has led an academic to warn of potential conflicts of interest.
The move underlines the rapid changes taking place in the school exams industry, with two of England's big three boards now expanding into areas such as teacher support and online tuition.
AQA chief executive Andrew Hall told The TES that it would be looking for further opportunities to broaden its services to schools.
"It is a really interesting time," he said. "Support that used to be provided by a number of different agencies may not be provided now and we will look for opportunities where we think we can make a difference."
Assessment expert Professor Alan Smithers said he was concerned about the risks posed to "dispassionate, independent assessment" if the organisations setting exams also offered services to help raise school achievement.
"If there can be a secure Chinese wall overseen by Ofqual, then it can work," the Buckingham University academic said.
"But there is always a fear that the business dynamic is about getting as many people as possible to take exams and making them as 'user-friendly' as possible.
"If you have got one part of the company selling resources and another supplying exams, then the resources side may well say, 'Why don't we put on some services about exams?' which may get down to advice on mark schemes and questions."
Mr Hall said Chinese walls separating different parts of AQA "would be the intention".
"These are not activities we are developing to market AQA assessments," he added. "There is absolutely no intention to do that."
Professor Smithers has already raised similar fears about Edexcel, the only one of England's big three exam boards in private ownership.
Edexcel is developing teaching aids and has been more closely integrated with its parent company Pearson, a major textbook publisher that has just set up a school-improvement business.
AQA is a charity, but Mr Hall said it would charge for some of the services it offered schools, to make surpluses that could be ploughed back into the organisation.
He said the purchase of Teachit, an online teacher resources community (The TES offers a similar service) was part of a diversification that he had accelerated since joining AQA last year.
"It is in our heart and soul to be more than an exam board," he said, "Our charitable purpose is to do good in education."
An Ofqual spokesman said: "We will not tolerate conflicts of interest that impact on the integrity of qualifications. We will be speaking to AQA to get further information about the acquisition of Teachit."