Communal strength refers to a person's degree of motivation to respond to a communal partner's needs. The development and testing of a questionnaire measure of communal strength is described. Study 1 involved item selection. Studies 2 and 3 found that the 10-item communal strength measure taps a construct distinct from behavioral interdependence as measured by the Relationship Closeness Inventory of Berscheid, Snyder, and Omoto (1989) and distinct from liking for the partner. As expected, the measure correlated highly with Rubin's (1970) Love Scale. Studies 4 and 5 found the measure predicted allocation of benefits to peers and reports of giving help to, and receiving help from, friends. Study 6 found that, when answered in relation to the respondent's spouse, the measure predicted the spouse's marital satisfaction, after controlling for the respondent's communal orientation and own marital satisfaction.