The investigators' hypotheses are: Low-dose testosterone augmentation improves depressive symptoms in women with Major Depressive Disorder (MDD) and antidepressant partial/nonresponse, adjunctive low-dose testosterone is safe and well-tolerated in women with MDD and antidepressant partial/nonresponse, and low-dose testosterone augmentation improves fatigue and sexual dysfunction.

Inclusion Criteria:

1. Female, age 21-75
2. Major depressive disorder including MADRS>/=12
3. Currently treated with an antidepressant monotherapy (1st, 2nd or 3rd trial in current episode), that has been taken at an adequate dose for at least six weeks.

Exclusion Criteria:

1. Serious suicide or homicide risk, as assessed by evaluating clinician
2. Unstable medical illness including cardiovascular, hepatic, renal, respiratory, endocrine, neurologic
3. Substance use disorder active within last six months, or clinical suspicion of ongoing substance use disorder at the discretion of the study clinician at time of screening based on history and/or laboratory results.
4. Any history of psychotic features, bipolar disorder, or primary obsessive compulsive disorder, as assessed by SCID
5. Currently treated with typical or atypical antipsychotic medications, or lithium
6. Untreated hypothyroidism. If treated hypothyroidism, change in levothyroxine dose within the prior 3 mos
7. Use of androgens, including testosterone, dehydroepiandrosterone (DHEA) and methyltestosterone, within the prior three months
8. Any investigational psychotropic drug within the last thirty days
9. In the judgment of the study clinician, unlikely to be able to participate safely throughout the study period (three or more episodes of self-harm in the past year, documented history of poor treatment adherence, or frequent missed appointments (>50%) in the past year)
10. ALT > 3x upper limit of normal or creatinine> 3x upper limit
11. History of a hormone-responsive cancer

8 weeks

Definition of serious adverse event is as defined on the clinicaltrials.gov website.