1. Open your existing query in ResearchPoint.
2. In the Field Explorer pane on the Output/Filters tab, expand the category 'Households Belonging to.' Click on the link for 'Household Constituent' under this category.
3. From the field list now displayed in the middle pane, drag 'Lookup ID' into your output. This will be the lookup ID of the household record that the individual is a member of. This will only be populated for people that are members of households (not for single individuals or organizations).