Software Product Line Engineering (SPLE) demands upfront long-term investment in (i) designing a common set of core-assets and (ii) managing variability across the products from the same family. When anticipated changes in these core-assets have been predicted with certain accuracy, SPLE has proved significant improvements. However, when large/complex software product line projects have to deal with changing market conditions, alternatives to supplement SPLE are required. Agile Software Development (ASD) may be an alternative, as agile processes harness change for the customer's competitive advantage. However, when the aim is to scale Agile projects up to effectively manage reusability and variability across the products from the same family, alternatives to supplement agility are also required. As a result, a new approach called Agile Product Line Engineering (APLE) advocates integrating SPLE and ASD with the aim of addressing these gaps. APLE is an emerging approach, which implies that organizations have to face several barriers to achieve its adoption. This paper presents a systematic literature review of experiences and practices on APLE, in which the key findings uncover important challenges about how to integrate the SPLE model with an agile iterative approach to fully put APLE into practice. Copyright © 2011 John Wiley & Sons, Ltd.