Some groups come together or “click” from the first time their members meet, while others labor for months or longer to be something other than separate and competing personalities. Creating an effective work group is part planning and part luck. Just as mixing chemicals produces different results depending on the substances and their quantities, combining personalities and work styles results in varied effects. Indeed, we often talk about the “chemistry” among group members as critical to the group's success. Changing just one member often alters the group far beyond that one member's role and responsibilities.