This is an empirical investigation of the nature of corporate strategic planning practices among major corporations operating in the ASEAN countries - Singapore, Malaysia, Thailand, Philippines and Indonesia. The study is structured along a hypothesis testing framework. The data was collected via mailed survey instruments (using mainly 5-point Likert-type scales) which were developed for each respondent type - the Chief Executive, Senior Manager, and Corporate Planner - and refined through pre-testing. Comparative analyses are made of inter-country and inter-industry differences in strategic planning practices. Hypotheses concerning the interrelationships of strategic, contextual and performance variables are then subjected to statistical testing. This study found interesting individual as well as patterns of correlationships between strategic-contextual, contextual-performance, and strategic-performance variables. The implications of these findings to management were discussed. Suggestions were also made as to the future directions of planning research.