It’s a manual two decades in the making, and it was already sparking controversy months before its release.

On Saturday, the American Psychiatric Association released the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a guidebook of diagnostic information for people with mental disorders that’s considered the “bible” of the mental health field.

APA, holding its annual meeting this week, has faced criticism about updates to the manual that reclassify a number of  ailments in significantly different ways. Critics say the manual has classified many normal emotional reactions, such as grief and anxiety, as “disorders” that require treatment, often with medication.

More details on how the association is handling the situation:

About the manual: In announcing DSM-5’s launch, APA noted that the manual had largely been restructured based on new information about the root causes of certain illnesses and that it would provide a better tool for mental health professionals. “The changes to the manual will help clinicians more precisely identify mental disorders and improve diagnosis while maintaining the continuity of care,” Dr. David J. Kupfer, who chaired the DSM-5 Task Force, said in a statement. [PDF] “We expect these changes to help clinicians better serve patients and to deepen our understanding of these disorders based on new research.”

The controversy: Some of the changes have raised red flags for doctors and the general public. In February, early information from the book reached the press. One change that drew attention was APA’s decision to drop Asperger’s syndrome and child disintegrative disorder as classifications, instead including them under the broader label of “autism spectrum disorder.” That revision, along with others, prompted a number of medical groups, led by the American Psychological Association’s Society for Humanistic Psychology, to sponsor a petition asking the association to reconsider the approach to the manual “not only as select individuals on a committee, but as a professional community.” The petition, backed by  numerous association members as well as other divisions of the American Psychological Association, has nearly 15,000 signatures.

The response: Kupfer explains that the DSM, long considered a key guidebook to psychiatric research, has evolved into a tool best used for clinical care. Thomas Insel, the head of the National Institute of Mental Health, notes that the goal of the manual appears to have changed. “The DSM is the best we’ve got for clinical care,” he told the Wall Street Journal. “It’s no longer the best guide for research. We’re at a point now [where] we’re ready to go to the next step.” Insel’s statement is notable because most NIMH research has previously required diagnostic criteria from DSM, and the way it classifies information has a major effect on grant funding, drug approvals, and medical billing.

While other classification options exist in the field, such as the World Health Organization’s International Classification of Diseases, the DSM has remained at the forefront of mental health research for decades.

APA President-elect Jeffrey Lieberman, who chairs the psychiatry department at Columbia University, says the issue is not the content of the manual but the way it is used by psychologists, psychiatrists, and other clinicians.

“We’re trying to establish accurate and reliable guidelines, and you can’t completely control how they’re applied,” he told Reuters. “The problem is not with the instrument but with the way it’s used.”