Since the introduction of middle management-driven model of strategy, researchers started to conduct studies on the upward involvement of middle managers. Undoubtedly, the Middle Management Involvement Model of Floyd and Wooldridge \(1994\) has created a milestone in the field. Following their model, more studies were performed to examine the perception, roles, behavior and organizational performance, but their findings were mainly confined to general environment without controlling for any contextual influence. Although some context-specific studies were conducted recently in the telecommunication and health care service industries, their findings were only confined to the contexts of dynamic internationalization process and government policy and professional bureaucracy. So there was a gap in literature, demanding for more context- and industry-specific studies, in order to enrich and validate the extant theories. This study intended to apply and extend Floyd’s and Wooldridge’s \(1994\) Middle Management Involvement model in the public utility sector through a qualitative case study. In this case study, a local public electric utility, CEM, was selected. It was under a monopolistic environment through its exclusive concession contract awarded by the government that allowed a guaranteed return on asset. Top and middle management were interviewed to examine how middle managers influenced the strategic adaptation. This study hoped to contribute to the strategy literature by \(1\) discovering the strategic involvement and influence of middle managers under a mature and stable market context; and \(2\) discovering how the strategies proposed by middle managers could contribute to the overall strategic planning process in a public utility company. The findings of this study revealed that Floyd and Wooldridge’s \(1994\) Typology of Strategic Roles might not be generally adopted by middle managers as certain context specificities might drive diminished effect and reduced willingness in practicing upward and downward influences under a non-competitive market. In this case, middle managers performed lateral influences to generate turnaround solutions to exert their influence for strategic adaptation. Moreover, these lateral influences were able to stimulate and improve the practicing of the other four strategic roles suggested by Floyd and Wooldridge \(1994\). As a result, a new Ecology of Middle Managers' Strategic Involvement was discovered. These strategic lateral influences are: Stimulating Strategic Nodes – To explore key “interacting nodes” along the value chain to uncover chances of enhancing strategic values by learning routines and requirements of their upstream or downstream counter-parts. Through this exercise, middle managers facilitated cross-functional learning that, in turn, stimulated review of own and counter-parts’ resource setting, operational routines and functional capabilities. Clustering Integrity – To create strategic integrity from the dispersed operational silos by re-building inter-dependencies and forming cross-functional partnership. Middle managers focused on securing common interest and common values with their counter-parts. Clustering Integrity could happen either at Single Process Based level or Global Structure Based level