PeerLibrary is a fresh project so vivid open source community does not yet exist around it. Current developers are meeting mostly in person and necessary technological and social infrastructure for new contributors has been missing. But in the course of the first assignment we were approached by two new contributors, Anna and Seema, which resulted in improving all those aspects and become more open to future contributors as well.
As a consequence we now have a development mailing list and improved README, better explaining how to setup a development instance of PeerLibrary and possible ways to start contributing and even just contacting others involved in the project.
Because even new contributors are local, we meet few times in person, to easier discuss basics and ideas, but at the same time we started encouraging online presence. For example, posting to the mailing list and using pull requests so that others can follow the development. This is especially important because we do already have some waiting and quiet members of the mailing list and we hope to engage them in this way as well.
I believe both active contributors and quiet members on the mailing list are interested in the project because of our hopes to improve ways science is being discussed online. While this brings us together, it is hard to find time to really work on the project. Technical knowledge for contributing does not really matter much here, because those with more technical knowledge are tackling bigger challenges which take time, and those with less are maybe tackling smaller challenges, but it takes them time as well. This is probably the reason why we have not many active developers. But it is seems that once there is an additional incentive, like opportunity to use work on PeerLibrary as a class project, it is easier to align interests in the project with time requirements.
This brings me to my past observation in other projects I have been involved in. You always need two incentives, two reasons, why you are participating in the project to really actively participate in it. Just interest is not enough. Sometimes is a personal need. Sometimes is an award. Sometimes is social recognition. Sometimes is a school project. Sometimes is a competition.