Competing only with one's own resources has meant to abandon opportunities and available resources from others. In this context many authors have emphasized the use of alliances as an effective solution to confront the global business. Most studies of inter-firm relationships have been done focusing on large firms but little is known about the study of cooperation and alliance involving small and medium enterprises (SMEs). This research offers a deep analysis of the alliance engagement of SMEs in many countries, it identifies four influential factors and proposes a model of the decision-making process to provide an orientation to SMEs that want to be involved in an alliance engagement.