Infant and Child Development Inf. Child Dev. 16: 135–149 (2007) Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/icd.502 Measuring Change: Current Trends and Future Directions in Microgenetic Research Emma Flynn a, * and Robert Siegler b a School of Psychology, University of St Andrews, St Andrews, Scotland, KY16 9JP, UK b Psychology Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA This special issue is dedicated to research that adopts the microgenetic method in order to investigates change as it is happening. In this commentary we reflect on the diversity of the articles included in this special issue, and examine how the findings from these articles relate to five critical features of change: path, rate, breadth, variability and source. The over- arching theme from these findings is that the tidy results reported in cross-sectional studies are not in fact as tidy as they originally appear. Most important, the untidiness within the data is informative when attempting to explain development and learning. In the second half of this commentary we highlight some current questions relating to the use of the microgenetic method: is the ’microgenetic method’ a method, a theory, or a philosophy; is change development, learning, or both; what is the relation between microdevelopment and macrodevelopment; and what is the next step for the microgenetic method? Copyright # 2007 John Wiley & Sons, Ltd. Key words: microgenetic; change; theory acquisition; cognitive development                                     Developmental psychology is at an exciting point, especially for researchers interested in understanding the process of change. Not only can developmental psychologists examine physiological indices associated with change by using fMRI and EEG, but advanced statistical tools allow increasingly vigorous analysis of repeated measure data. An extensive tool-box is now available for researchers interested in cognitive development. This special issue provides a stimulating, informative and innovative set of articles related to the use of a methodological tool aimed at examining the process of change, the microgenetic method. The greatest benefit of the microgenetic method is that it allows individual profiles of performance to be: (i) recorded, to provide an indication of what the *Correspondence to: Emma Flynn, School of Psychology, University of St Andrews, St Andrews, Scotland, KY16 9JP, UK. E-mail: egf1@st-andrews.ac.uk Copyright # 2007 John Wiley & Sons, Ltd.