Positivity resonance—defined as a synthesis of shared positive affect, mutual care and concern, plus behavioral and biological synchrony—is theorized to contribute to a host of positive outcomes, including relationship satisfaction. The current study examined whether, in long-term married couples, behavioral indices of positivity resonance (rated using a new behavioral coding system) are associated with concurrent shared positive affect using a wellestablished dyadic-level behavioral coding system (i.e., Specific Affect Coding System: SPAFF), and whether positivity resonance predicts concurrent marital satisfaction independently from other affective indices. Long-term married couples completed a self-report inventory assessing marital satisfaction and were then brought into the laboratory to participate in a conversation about an area of marital disagreement while being videotaped for subsequent behavioral coding. Inter-rater reliability for positivity resonance behavioral coding was high (intraclass correlation coefficient: 0.8). Results indicated that positivity resonance is associated with frequency of shared positive affect using SPAFF. No associations were found between positivity resonance and frequencies of SPAFF-coded individual-level positive affect or shared negative affect. Additionally, positivity resonance predicted marital satisfaction independently from frequencies of SPAFF-coded shared positive affect and individual-level positive affect alone. The effect of positivity resonance on marital satisfaction also remained significant after controlling for overall affective tone of conflict conversation. These findings provide preliminary construct and predictive validity for positivity resonance behavioral coding, and highlight the possible role positivity resonance may play in building relationship satisfaction in married couples.