Self-reported parental stress was investigated in three samples of mothers with small children, using a Swedish version of the Parenting Stress Index (PSI). Dimensionality in experienced stress using items from six PSI Parent Domain subscales and eight new items was examined in factor analyses of data from a nationwide representative sample. Cross-validation proved the chosen factor pattern to be stable. Based on an oblique 5-factor solution new subscales were constructed. A second order factor analysis indicated influence from a higher order factor, seen as a general parental stress construct. High alpha coefficients revealed that homogeneous subscales had been formed. Test-retest correlations indicated good stability over a mean time period of 30 days. Influences from maternal background variables were found, but no relation to child age or gender. Global estimates of parental stress, reported child problems, mothers' scoring on the Edinburgh Postnatal Depression Scale and two measures of social support all correlated significantly with overall parental stress, and with some subscales. The justification of the subscale approach to parental stress was discussed. It was concluded that the PSI in its present form could be used as a reliable and valid instrument for measuring experienced parental stress in mothers of young children.