The engagement of firms in multiple simultaneous strategic alliances with different partners has become a ubiquitous phenomenon in today’s business landscape. This article offers a review of the extant alliance portfolio literature and organizes it around three key research areas: (a) the emergence of alliance portfolios, (b) the configuration of alliance portfolios, and (c) the management of alliance portfolios. The article also highlights existing gaps in the present understanding of alliance portfolios and outlines a research agenda by identifying key research questions and issues in the areas where further research is needed.

The authors content analyzed self-reported limitations and directions for future research in 1,276 articles published between 1982 and 2007 in the Academy of Management Journal, Administrative Science Quarterly, the Journal of Applied Psychology, the Journal of Management, and the Strategic Management Journal. In order of frequency, the majority of self-reported limitations, as well as directions for future research, pertains to threats to internal, external, and construct validity issues, and there is a significant increase in the reporting of these elements over time. Longitudinal analyses revealed that some of these increases varied across management subfields (i.e., business policy and strategy, organizational behavior, organizational theory, and human resource management), indicating unique research contexts within some research domains. Based on the analyses of self-reported limitations and future research directions, the authors offer eight guidelines for authors, reviewers, and editors. These guidelines refer to the need for authors to report limitations and to use a separate section for them and the need for reviewers to list limitations in their evaluations of manuscripts; authors and reviewers should prioritize limitations, and authors should report them in a way that describes their consequences for the interpretation of results. The guidelines for directions for future research focus on positioning them as a starting point for future research endeavors and for the advancement of theoretical issues. The authors also offer recommendations on how to use limitations and future research directions for the training of researchers. It is hoped that the adoption of these proposed guidelines and recommendations will maximize their value so that they can serve as true catalysts for further scientific progress in the field of management.

The engagement of firms in environmental collaborations has become a ubiquitous phenomenon in today’s business landscape. Yet much of the research to date is fragmented across multiple disciplines and lacks a clear framework to support future study. The authors consolidate and synthesize existing contributions into a conceptual map comprised of antecedents, consequences, and contingencies to better understand environmental collaborations. This map offers a perspective on how firms develop strategies, structures, and capabilities to manage and balance environmental and economic performance and increasing demands for environmental sustainability from multiple stakeholders and society. The authors then highlight existing gaps in the extant literature and outline a future research agenda, including key questions and issues needing additional study.

International audienceWe examine how new network resources accessed through alliance formations interact with network resources present in a firm's alliance portfolio. We test our theoretical model using event study methodology and data from the global air transportation industry. We find that the market rewards firms forming alliances that contribute resources that can be synergistically combined with firms' own resources as well as with network resources accessed through their alliance portfolios. Our results also indicate that the market penalizes firms entering into alliances that create resource combinations that are substitutes to resource combinations deployed by existing alliance partners

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