Learning affordances of an e-learning environment are defined as properties of the user interface that enhance pedagogically meaningful activity patterns. This paper proposes the Soft Ontology of Learning Affordances (SOLA) framework for analysing and designing the properties of the social software tools: blogs, wikis, social recommendation tools etc. The process of deriving tool affordances from the evaluation of e-learning activities is described, and its applicability in learning designs with social software are elaborated. Research questions- How could the Activity Theory and Soft Ontology approach be applied for evaluating the learning affordances of social software? - What are the main factors influencing the use of SOLA framework in designing and analysing Personal Learning Environments involving social software? When e-learning activities are carried out in an institutional Learning Management System, the users (facilitators and learners) are not involved in choosing the tools or customising the learning environment. However, the situation is radically different in the distributed and highly personalised landscape of social software tools - the users themselves would have to create pedagogically meaningful ways of using these tools. Selecting the right tool for a learning task cannot gain much from the general or technical description of the tool, the users need support for selecting tools according to their pedagogical affordances. The concept of affordances assumes that the properties of tools applied by users are dependent on the context of the activity and their action goals realised during the activity (Rasmussen and Vicente, 1992). Bärentsen (2000) has shown that learners' perception of tool's pedagogical affordances changes dynamically during the activity. The affordances of social software tools depend also on how different tools are combined in the activities. This makes the learning affordance driven analysis of the social software tools not a trivial task and calls for a flexible way of defining the learning affordances. We propose to use Soft Ontology approach for describing a fuzzy set of user-created meanings and user-defined properties of learning activities. Dataset has been collected from the series of e-learning activities conducted in Tallinn University in 2006-2007. Dense activity descriptions using pedagogical activity pattern language were composed collaboratively by research team using the SOLA framework. Two researchers will then evaluate independently the pedagogical affordances of each tool using activity descriptions, characterizing the role of events, subjects, tools and artifacts in learning activities at the operational level. SOLA of these tools will be defined, explaining how each tool supports specific actions and operations in the context of pedagogical activities. Interviews with users about the merits of using SOLA for selecting social software will be conducted.The SOLA framework builds on the Activity theory (Engeström, 1987) and Unified Activity Management framework (Moody et al., 2006). Subjects (their roles and rules in the community), artefacts embedded in the system or created by learners (with different domain context and meaningfulness to learners), and tools (with certain technical properties and affordances for learning) mediating the activity would develop constraints to each other, narrowing down possible actions and operations people can take for realising their learning goals. As the work is still in progress, the results will be presented on the ECER 2007 conference. Bärentsen, K. B. (2000). Intuitive user interfaces. Scandinavian Journal of Information Systems 12, 29-60.Moody, P., Gruen, D., Muller, M. J. , Tang, J., Moran, T. P. (2006). Business activity patterns: A new model for collaborative business applications. IBM Systems Journal, 45(4), 683-694. Engeström, Y. (1987). Learning by expanding. Helsinki: Orienta-konsultit. Vicente, K., Rasmussen J. (1992). Ecological interface design: Theoretical foundations. IEEE Transactions on Systems, Man and Cybernetics, 22(4), 589-606