The purpose of this study was to examine the cognitive processes related to interaction episodes in improvisation through the development, testing, and validation of a rubric for assessing interaction in improvisation. Four questions guided this study: (a) is a rubric an effective method for assessing performance achievement at undergraduate, graduate, and professional levels? (b) what is the interjudge reliability of a rubric used to assess interaction in improvisation? (c) which of the rubric criteria maximally differentiate 3 performance achievement levels (i.e., undergraduate, graduate, and professional)? and (d) does a cognitive task ordering of difficulty exist in assessing interaction? The rubric consisted of 3 melodic interaction criteria, 2 harmonic interaction criteria, and 3 rhythmic interaction criteria. A total of 55 expert judges evaluated 55 distinct improvisation performances. The results indicated a statistically significant multi- variate analysis of variance effect across all 3 performance achievement levels on each rubric item. The standardized discriminant function coefficients suggested that the 3 performance achievement levels were maximally differentiated by a canonical variate with greater weightings from all 3 melodic interaction criteria (i.e., Reactiontoimplied[melodic] musicalsuggestions, Developmentofmelodicmusical ideas stemming from motivic interplay, and Adaptation to melodic interplay [call and response]) and 1 rhythmic interaction criterion (i.e., Coordination of rhythmical pulse [timing and synchronization]). The results indicated a cognitive ordering of rater task difficulty: melodic interaction, rhythmic interaction, and harmonic interaction. A total of 66.33% of the variability was accounted for by performance achievement level, and interjudge reliability was estimated using Cronbach's alpha (α - .91).Keywords: assessment, cognition, jazz, improvisation, interactionInteractive episodes are often considered to be the foremost contributor of excitement and complexity in a performance (Berliner, 1994, 1997; Hodson, 2007; Monson, 1996). According to Monson, Good improvisation is sociable and interactive just like a conversation; a good player communicates with the other players in the band. If this doesn't happen, it's not good jazz (p. 84). A difficulty in evaluating and measuring interaction epi- sodes in improvisation lies in judging the ensembles' overall performance achievement and creativity level (Collier, 1995). Re- search studies related to improvisation creativity and perfor- mance achievement often exclude the variable of interaction due to the complexity of measuring performers' cognitive and decision- making processes (Ciorbia, 2009; Limb & Braun, 2008; Madura, 1995; May, 2003; Norgaard, 2011; Smith, 2009; Ward-Steinman, 2008). Other studies acknowledge the collaborative nature of improvisation but maintain that temporal cognition is evident only in real-time improvisational performance (Johnson-Laird, 2002; Mendonca & Wallance, 2004; Pressing, 1984). An additional problem with the evaluation of interaction in musical performance lies in the perception of observed behaviors. Interaction within an improvising ensemble may not always be detected by observ- able behaviors; in particular, the presence of subconscious cogni- tive and affective behaviors can potentially obscure the ability to perceive interaction by both the observer and the participants themselves (Seddon, 2005).Further investigation into the cognitive processes of interaction and performance achievement level is needed in order to broaden the scope of teaching and learning in performance. The purpose of this study was to examine the cognitive processes related to interac- tion episodes in improvisation through the development, testing, and validation of a rubric for assessing interaction in perfor- mance. …