Abstract||Organisations are increasingly reliant on effective information systems (IS) yet little is known about the information and influences that contribute to their selection. Decision makers play an important role in the evaluation, acquisition and implementation of information systems in organisations. Their role during the re-implementation phase of information systems projects is critical, yet little is known about how and why these decisions are made. This thesis explores the influences on these decisions and reports their effects. The aim of this research is to increase the understanding of what occurs during decision making in the critical pre-implementation phase. A cross-disciplinary approach has been employed to develop a research framework informed by literature from information systems, innovation and adoption theory, management decision making and organisational decision making. A qualitative research method was used to develop four exploratory case studies. Research was conducted in private and government organisations that had implemented large information systems. An interpretive hermeneutic text-based analysis technique was used in a cross-case analysis in order to build theory and address the research questions. Fifty-six informational and contextual factors were identified in this research as having effects on information systems pre-implementation decision making. These factors fall into eight broad thematic factor groups: confidence, decision process, opinions, option attributes, organisation, perceptions, politics and vendor attributes. This thesis concludes that there are linkages between decision factors and decision outcomes. It is argued that to achieve positive decision outcomes from information systems preimplementation
decisions, conditions for intra- and inter-organisational alignment must exist. It is also argued that information systems re-implementation decision outcomes alter intra- and inter-organisational alignment conditions and affect future decisions.