Purpose - This paper aims to examine the relationship between key contextual factors (type of strategic investment decision-making (SIDM), decision uncertainty, organizational goals, financial and non-financial corporate performance, firm size, and decision-maker background) and three significant dimensions of SIDM processes (procedural rationality, strategy formulation and political behaviour). Design/methodology/approach - A survey was mailed to the financial directors of manufacturing companies selected from the UK Financial Analysis Made Easy database. Factor analysis and multiple regression analysis were used to analyse the survey results. Findings - The findings reveal that SIDM is more complex and less systematic than the normative literature suggests, with a combination of contextual factors influencing the decision-making process. Further, the regression results suggest that SIDM is shaped by the interplay of procedural rationality, strategy formulation and political behaviour and that none of these on its own can sufficiently explain SIDM practice. Research limitations/implications - The survey data are drawn from UK manufacturing companies, so the findings may not be generalisable beyond that context. Practical implications - The findings suggest a need for firms to recognise that strategy formulation and political aspects of decision-making are as important as "rational" financial analysis in SIDM practice. Further, since SIDM practice is shaped by a combination of contextual factors, a comprehensive overview of these factors is necessary to direct SIDM outcomes. Originality/value - This study adds to the limited prior research examining the links between contextual factors and SIDM processes. Prior studies have tended to focus on only one dimension, or on limited factors, and have reported inconsistent findings. This paper provides a broader view of the complex nature of SIDM processes.