In the last few years, Open Source Software (OSS) has been widely accepted and adopted, but there still are several concerns on how much trustworthy OSS actually is, and how its trustworthiness can be evaluated.

These doubts led to a much lower adoption rate than expected. We are interested in what OSS users think about OSS trustworthiness, so we can then devise evaluation methods for OSS that are useful to users in general and the European software industry in particular.

The objective of the investigation documented in this report is twofold:

1. to understand the reasons and motivations that lead software companies to adopt or reject OSS and software developers to develop OSS
2. to understand which specific trust factors are taken into account when selecting an OSS product.

We interviewed quite a few representative industrial organizations and several people with various professional roles. We report the insights in OSS trustworthiness deriving from the statistical analysis of the results of the interviews, as well as on the review of the relevant literature.