Theory building is a dynamic process. Theories develop and grow, they are dependent on initial conditions, social interactions, variation, and they are stable for some time only to move on to the next phase. They can develop gradually, but a non-linear pattern is more common. Most importantly, theories develop over time. Theories are typically based on shared cognitions and they are situated. Written descriptions by definition reflect versions of the theory that are outdated the moment they are in print, though some of the core assumptions may be more stable than other, more peripheral ones. All of this very much applies to the present discussion of our paper on a DST approach to SLA. Inevitably, we, and probably most of the commentators, will already have moved on in our thinking about DST and SLA by the time this comes into print. In particular with new approaches, we will see a great deal of variability: wild ideas flourish and the links between grand theoretical notions and empirical database to support them tend to be out of balance. That may be seen as a weakness, but it probably is an inevitable developmental stage in building a new theory, or, as in this case, the application from a theory developed in other fields to SLA.