This paper serves four purposes. First, it provides an introduction to the series of conference sessions on Household Panels and Longitudinal Data Analysis. Second, it gives a brief overview of the European Science Foundation (ESF) Network on Household Panel Studies which coordinated these sessions. Third it addresses some of the methodological themes which are less well covered within the limited time frame of the sessions, especially with regard to data collection and data quality issues bearing on problems of measurement error. Finally it offers examples from the British Household Panel Study of forms of methodological research which are particularly relevant to improving the quality of household panel studies and provides some speculati...