Drawing on an economic, value-based framework of creative idea appraisals, we predict that the attributes of idea usefulness and novelty jointly inform people's decisions to allocate time toward collaborative implementation efforts. In a correlational design, we found support in our first study (n = 82) for an interaction between perceived idea usefulness and novelty. Specifically, perceived novelty reduced the effect of usefulness on effort (time invested) in implementation planning. Using experimental methods in our second study (n = 162), we applied expectancy theories to explain the subjective judgments behind why people might withhold effort when developing and planning the implementation of others' creative ideas. Results of this study revealed that perceived instrumentality of implementation activities mediated the joint effects of idea usefulness and novelty perceptions on implementation planning effort (as self-reported effort and time invested). Together, both studies highlight the importance of idea appraisals in determining implementation behavior. Practical implications about cultivating support for the final production of creative ideas are discussed.