The aim of this article is to present a situation of observation designed for the assessment of family interactions: The PicNic Game (PNG). In this situation, families are invited to play at having a picnic together. This can be done with any number of children, aged from a few weeks to adolescence. A companion assessment tool, the Revised-Picnic Assessment Scale (Re-PAS), allows evaluation of interactions in the family on several dimensions. This article presents the PNG and a preliminary study of the validation of the Re-PAS dimensions in a sample of families (N = 67) with 18-month-old infants and their siblings. The PNG was well-received by the families. Construct validity of the Re-PAS was tested, first against self-reported data by mothers and fathers regarding marital satisfaction, coparenting behavior, and division of household tasks, and then against observed maternal and paternal sensitivity and controlling behaviors assessed during free-play. Results show satisfactory preliminary reliability and validity. Two contrasting cases are presented to illustrate the different interactions highlighted in the PNG. This situation is useful for researchers and clinicians, particularly as a basis for video-feedback work with the family.