The present study examines effort in narrative creative writing (operationalized as time-on-task) using a new assessment approach, the storyboard task. Participants (N = 125) completed alternate forms of the storyboard task in two sessions five weeks apart. They also completed measures of divergent thinking and self-reported ideational behavior. Time-on-task, story length, and rated creativity scores were obtained for the participants' stories. The storyboard task demonstrated good alternate form reliability and convergent validity with the criterion measures. Although time-on-task was strongly, positively associated with creativity scores, this relationship was confounded by the contribution of story length. Relationships amongst these variables were similar when creativity was rated by novice raters using a rubric or experienced raters using the consensual assessment technique. Additionally, story length and time-on-task were moderately correlated with the external criterion measures of creativity. Thus, the strong associations between rated creativity, story length, and time in creative writing raise important issues and avenues for future research, and results for the storyboard task suggest that it is a valuable assessment of narrative creative writing.