Research Objective: The core purpose of this study was to gain a deeper understanding of the nature and characteristics of leadership styles or behaviors that are most suited for successful execution of transcultural projects with multi-ethnic participants. Research Problem: Projects are temporary organizations, and a lack of effective project leadership—an under-researched and less apparent ‘soft’ area of project management—has been cited as a major cause of costly project failure, overriding most organizational factors. Studies often point to interpersonal and behavioral problems as the root causes of project failure. Today, the challenge of project leadership is compounded by cross-cultural factors as projects around the world are being increasingly peppered with multi-ethnic participants. To this end, the overarching research question underpinning this study is: What are the leadership characteristics that compose an effective transcultural project leadership model for leaders of projects as temporary organizations composed of multi-ethnic teams? Theoretical Background: A thorough literature review revealed that there was no single theory that could fully explain the constituents of effective project leadership, specifically in a transcultural environment. This study therefore argued for a need to incorporate the unique characteristics of a fast-paced, time-limited and goal-driven project as a temporary organization with a diversity of cultures. With Bass & Avolio’s (1990) ‘Full Range of Leadership Theory’ (FRLT) as the primary theoretical base—supplemented by cross-cultural, project management, and team dynamics theories—a conceptual model of Transcultural Project Leadership (TPL) was developed, undergirded by six theoretically derived hypotheses. A new Cross-cultural Project Leadership (CPL) framework and associated measurement scale were also crafted in this study. Research Design and Methodology: Commensurate with the multi-disciplinary theoretical underpinnings and complexity of the conceptual TPL model, a multi-method, three-stage research design was adopted. The TPL model was operationalized by the MLQ-5X, as well as the Cross-cultural Project Leadership (CPL), and Project Success Measures (PSM) instruments. A stratified, balanced sample pool of 361 international project practitioners comprising transcultural project managers (PMs; n=213), multi-ethnic team members (TMs; n=94), and managers of international project portfolios (MoPs; n=54) were drawn from around the world and directed to a composite, pre-tested, and web-based MLQ-CPL-PSM survey. The three stages of the study were as follows: • Study I: Interviews of transcultural project personnel to ascertain key cross-cultural project leadership (CPL) framework variables to confirm and supplement evidence of these variables from the organizational, cross-cultural, project management, and team dynamics literature; • Study II: Expert reviews and pre-test by senior academicians and seasoned project practitioners for essential validation of the newly developed Cross-cultural Project Leadership (CPL) survey instrument based on the literature review, and the primary research of Study I; and, • Study III: Survey of PMs, TMs, and MoPs using the composite, web-based MLQ-CPL-PSM instrument; detailed quantitative and qualitative analyses to test the conceptual TPL model and the six hypotheses; post-survey qualitative analysis of interviews of international PMs to enable refinement of the conceptual TPL model and development of a parsimonious theoretical TPL model; crafting of a consolidated TPL measurement instrument culled from the composite MLQ-CPL-PSM instrument and informed by the study findings; and, the proposition of a preliminary Theory of Transcultural Project Leadership (TPL). Results: The results of the research confirmed to various extents the six hypotheses of this three-stage study. Key findings were: (1) Passive-avoidant leadership styles are best avoided in transcultural projects; (2) Contingent-reward-based leadership is ineluctable in transcultural projects; and, (3) Concurrent use of transformational (TF), transactional (TR), and cross-cultural project leadership (CPL) has a cumulative and synergistic ‘augmentation’ effect, precipitating ‘exceptional performance’ by participants of the transcultural project. Contributions, Limitations, and Future Directions: This novel research at the confluence of organizational leadership, cross-cultural management, project management, and team dynamics identified behavioral patterns likely to result in effective transcultural project leadership. It extends the above knowledge to percolate even further into cognate literature—such as, organizational behavior, operations management, and international human resource management. For project practitioners and international managers, this TPL study has yielded ‘best practice’ guidelines for training and evaluation in transcultural project environments. Key limitations of the study included a relatively small sample size, cross-sectional data, and uneven distribution of industries and nationalities. Nonetheless, this research will serve as a springboard for widespread testing and refinement of the nascent theoretical model of TPL in diverse industrial and geographical settings—towards consolidation of a pithy and robust Theory of Transcultural Project Leadership.