Substandard and falsified medicines that find their way into the pharmaceutical supply chain short circuit the efforts of health care systems around the world. On a global health scale, medicines that deliver inappropriate amounts of active ingredient(s) can lead to increased mortality and morbidity. Medicines with reduced active ingredients can encourage antimicrobial resistance and can increase the likelihood of transmission for communicable diseases. On an individual scale, this translates to time, money and lives lost to treatable diseases. My thesis research addresses this problem and has focused on the development of analytical tools for pharmaceutical screening in low resource settings, such as developing countries where the problem is most prevalent. My work pairs an inexpensive paper platform with both chemical and biological detection methods. Chemical test cards combine twelve different colorimetric tests arranged in lanes to produce unique "color bar codes" for several pharmaceuticals, including beta lactam antibiotics and anti-tuberculosis medications. Working with the United States Food and Drug Administration, I was able to use these test cards to identify a collection of counterfeit pharmaceuticals by recognizing deviations from authentic formulations. While the chemical test cards are rapid, sensitive, and specific with an assortment of pharmaceuticals, there remains a group of pharmaceuticals that do not produce a unique color bar code with the test cards. To complement the chemical tests, I have also developed a biological paper-based test card that incorporates engineered yeast, which have the ability to respond to compounds with high specificity. My work details the development, optimization and evaluation of this biologically based test that can identify the presence of doxycycline in pharmaceutical dosage forms. It is my hope that these analytical tools and others like them can be used in low resource settings to better define the problem of substandard and falsified medicines, to identify poor quality medicines before they reach patients, and to address global health problems where they exist.