In 2018 and 2019, as part of the UK Legal Deposit Libraries’ sponsored ‘Emerging Formats’ project, the British Library’s digital preservation team a program of research into the preservation of new forms of content. One of these content types was eBooks published as Mobile Apps. Research considered a relatively small number of apps in an attempt to better understand the preservation challenges associated with them and make recommendations for a way forwards. It found that whilst the content landscape is extremely varied, the technical challenges are similar for both Android and Apple apps. The greatest challenges appear to lie in the acquisition and access areas, particularly in enabling delivery to appropriate rendering environments and devices, though other challenges remain around the use of device sensors and content stored on remote servers rather than the user’s device. Whilst these challenges may be surmountable with sufficient resource and investment, the lack of growth in this content area in recent years makes large scale investment questionable.