Hi, The boost library contains a circular buffer template by Jan Gaspar. It seems well written and STL robust, but I believe the design has some performance shortcomings in many practical usages. Every time I have used a circular buffer it has been to drag a window over a huge or real time dataset. If the dataset is non real-time and small enough to be contained in memory, there is no practical need for a circular buffer, since the window data pointer can just be dragged in memory along the full length of the dataset. In many algorithms using a dragged window, you would need to process the full length of the window for each time the window is moved. E.g. convolving signal data. Thus, you read from the window a lot more than you write. To maximize performance of your window reading and to utilize external libraries, you need linear access to the data. While Gaspar's circular buffer provide a linearize method, it requires a full reorganization of the contained data. This yields an O(N*M) efficiency, just for dragging the window (size N) over the data (size M). For internal use, the circular buffer provides iterators, but each iteration requires an internal buffer check, in order to wrap around the buffer border. Since the nature of a circular buffer in most practical scenarios (at least that I can think of) is to be involved in the processing of large amount of data, read performance is important. If you allow the internal buffer to allocate more memory than the size of the circular buffer, you can reduce the number of times you need to reorganize the internal buffer to make it linear readable. If you allocate N items more than the circular buffer size, you only need to reorganize every N+1 pushes to the window. Thus, allocating additional 100 items will reduce the reorganization overhead to 1%. I have written to Jan Gaspar, who recognizes that the buffer is not efficient for linear use, but he hasn't got the time anymore to add that feature. Is a circular buffer variant with linear access at a low maintenance cost something that would have public interest? Soren