This study explores the field of scientific policy advice in environmental and energy policies in France to gain insights into the role of think tanks. The field evolved along with the growth of think tanks. The think tanks refer to several orders of worth and combine them in their communication in order to qualify their expertise. The results of the study reveal that the think tanks have become more independent actors and that the field of scientific policy advice has gained autonomy. Both aspects indicate that the relationship between politics and expertise has gradually changed in France.