Agile is an established software development methodology that helps develop software by improving time to market, quality, customer engagement and reducing costs. Factors underpinning its adoption have been widely researched. However, most of these studies have been conducted in developed countries, particularly Europe and North America, with only a handful carried out in developing countries, including the Middle East. This is problematic given the strategic and economic importance of the software industry in such places as Saudi Arabia, where Agile adoption remains in the early stages, despite heavy investment in this industry in recent years to diversify its oil-dependent economy. Therefore, this study empirically investigates the factors influencing Agile adoption by Saudi Arabian software small and medium-sized enterprises (SMEs). To this end, in-depth interviews were conducted with 12 software practitioners from three software SMEs. Our findings reveal that human factors, such as customer involvement, team capability, organisational culture and national culture, are considered the most impactful factors affecting the adoption of Agile as opposed to technical ones, such as the availability of specific tools or techniques.