[eng] Measuring Individual Time Preferences . Microeconomic theory makes a saver’s choices dependent on the lifecycle of his discount rate, or on the subjective discount rate he uses to anticipate his future gratifications. The higher this rate, the lower the savings level. This time preference, characteristic of the agent’s life expectancy, needs to be differentiated from the parameters that govern his decisions as regards other timeframes: his extent of shorter-run impatience, but also his intergenerational altruism. Just as the discount rate compares a deferred gratification with gratification today, the extent of altruism indicates the relative weight placed on the welfare of one’s children - or the welfare of future generations - compared with one’s own welfare. A specific questionnaire has been put to a sub-sample of the 1998 INSEE Patrimoine survey on personal wealth to evaluate these individual preferences. To avoid the problems encountered by previous measurement attempts, the questionnaire contains the usual choices - between pleasures assumed equivalent on different dates -, but also puts a range of simpler and more concrete questions seeking to better identify what the time preference really represents in terms of decisionmaking period and "life plans”. By covering a large number of areas and situations, we hope to limit context effects and better control the other factors involved in intertemporal choices: interest rates, attitude to risk under a necessarily uncertain future, liquidity constraints, etc. The discount rate, impatience and extents of altruism - family and non-family related - are then evaluated by scores, ordinal measures that summarise the interviewee’s responses to all the questions attributed to each preference. Who is provident - low short-run time preference - impatient or altruistic? The explanatory regressions on the different scores generally produce the expected findings. Time preference appears to be transmitted through the mother. It is lower among seniors, qualified individuals, those in couples and those with children. In effect, most of the interviewees whose time preference is found to have changed consider that they have become more prudent as they have got older. A high level of education is positively correlated with both forms of altruism - family and non-family related. However, short-run impatience, an indicator we knew to be composite, does not depend on household characteristics. The only surprise is that women do not appear to be more provident or even more altruistic than the men as regards their children. [fre] Mesurer les préférences individuelles à l’égard du risque . Sensibles aux dimensions plurielle et variées des comportements face au risque, les développements récents de la microéconomie de l’incertain multiplient à l’envi le nombre de paramètres individuels de préférence - aversion au risque, prudence, tempérance, aversion à la perte, etc. - pour en rendre compte. De même, les études expérimentales ou de terrain cherchent à cerner cette diversité en dis...