<p>This study explored the factors that influenced teachers' Information Communications Technology (ICT) adoption in teaching and learning, and the adoption of an ICTPD innovation by 44 teachers in four schools in Malaysia. The research focused on understanding teachers' uptake of ICT in teaching and learning in the context of an Information Communications Technology Professional Development (ICTPD) programme, which was implemented in these four schools. This in-school and cluster based ICTPD programme, which was introduced from New Zealand, was the first of such projects carried out in Malaysia. To address the study's research questions, a collective case study approach was applied. It employed a qualitative approach through the use of mind maps, factor sheets, and semi-structured interviews as the major methods of data collection. The qualitative data was gathered from teachers who participated in the ICTPD programme. Other stakeholders were also included to ensure different perspectives were acquired in understanding teachers' uptake of ICT in the context of the ICTPD programme. An ecological framework, which incorporated complexity thinking, was employed to inform many aspects of this study, from the selection of methods to the analysis of the data. This framework assumes that factors influencing adoption are complex, interdependent, and independent; it assumes linear factors and linear stages in adoption do not explain the complexities of adoption. The research revealed that teachers' ICT adoption in teaching and learning was low and superficial. Teachers used ICT as a tool and their practices remained teacher-centred. Teachers perceived that their practices changed when they used ICT in their classroom but very few actually did. The ecological framework identified three levels of linear factors (individual, school, and external). The consequent application of the ecological-complexity perspective on these linear factors revealed complex factors and dynamic interactions between teachers within schools. The study also discovered that the uptake of the ICTPD programme was similarly superficial. Teachers and schools were reluctant to embrace the in-school facilitation process and the cluster model of the ICTPD programme due to the current priorities of delivering examination results. The findings initially showed the influence of three levels of factors (individual, school, and the innovation) on teachers' adoption of the ICTPD programme. An analysis of the factors according to the ecological-complexity perspective shed light on the extent of adoption and its processes, suggesting that teachers and schools dynamically negotiate with the innovation. Two ecological-complexity models were developed to explain and understand complex factors and interactions in the two types of adoption. The ecological-complexity perspective showed that the current discourses on linear factors and processes do not fully explain the complexities of teachers' ICT adoption and the uptake of an innovation. The discussions on practical applications for this perspective in education are examined. The ecological-complexity perspective highlights the importance of re-thinking our frames of understanding teachers' ICT adoption and the adoption of an ICTPD programme; instead of thinking about adoption as an end product, it is a dynamic and continuous process, which is negotiated between teachers and schools and the innovation.</p>