Oppositional Defiance Disorder (ODD)
What is ODD?  Basically, ODD is negative or hostile behavior that is beyond the norm.  Have you ever known a child that would argue with a brick wall and win?  That is ODD at it's finest.  The Diagnostic and Statistical Manual IV edition includes the following criteria for Oppositional Defiance Disorder:
A.  A pattern of negativistic, hostile, and defiant behavior lasting at least 6 months, during which four (or more) of the following are present:
  1.  often loses temper
  2.  often argues with adults
  3.  often actively defies or refuses to comply with adult's request or rules
  4.  often deliberately annoys other people
  5.  often blames others for his or her mistakes or misbehavior
  6.  is often touchy or easily annoyed by others
  7.  is often angry or resentful
  8.  is often spiteful or vindictive

Note:  Consider a criterion met only if the behavior occurs more frequently than is typically observed in individuals of comparable age and developmental level.

B.  The disturbance in behavior causes clinically significant impairment in social,
academic, or occupational functioning.

C.  The behaviors do not occur exclusively during the course of a Psychotic or Mood Disorder.

D.  Criteria are not met for Conduct Disorder, and, if individual is age 18 years or older, criteria are not met for Antisocial Personality Disorder.
Associated Features:
  Learning Problems
  Depressed Mood
  Hyperactivity
  Addiction
  Dramatic or Erratic or Antiscocial Personality
Differential Diagnosis:

Some disorders have similar or even the same symptoms.  The clinician, therefore, in his/her diagnostic attempt has to differentiate against the following disorders which need to be ruled out to establish a precise diagnosis:

Conduct Disorders;
Mood Disorders;
Psychotic Disorders;
Attention Deficit/Hyperactivity Disorder;
Mental Retardation; impaired language comprehension;
Typical feature of certain developmental stages.


Personal Note
No one really knows what causes a child to have ODD.  You will hear that it is hereditary, that it is a result of the child not bonding with the parent,  that it is a result of bad parenting.  You will even hear many claim that ODD does not exist, that it is an excuse by parents to explain rotten kids.  Yet the truth is, ODD does exist and no one really knows what the cause is. 
What matters is what can be done to help the child with ODD, this is what is important.  Treatment for ODD normally consists of a combination of behavioral therapy and medication, with a heavy emphasis placed on behavioral thereapy.  Consistecy is a must, rules must be stated in clear terms and consequences adhered to.  It is not an easy task and there will be days when all you can do is sit and cry from frustration.  But there is hope!  With the strides being made in behavioral therapy today and in the world of medicine, there is always hope!
Like many other disorders, ODD is often accompanied by other problems, such as ADD or Tourettes.  Therefore it is imperative that these be looked for as well when a diagnosis is being made.  And it is important to remember that ODD, like ADD and many other behavioral or psychological disorders, is diagnosed using observation of the child and by the doctor interviewing the parents and teachers.