The overdose epidemic remains one of the most pressing public health issues in the United States. The epidemic started with the increased availability of prescription opioids. Later, when access to prescription opioids was limited by prescribers due to an increase of dependency, many people turned to illicit heroin use. Illicitly manufactured fentanyl, which has a potency 50 to 100 times greater than morphine, was then introduced into the heroin supply causing another spike in overdose deaths. As drug overdose deaths across the United States continue to rise, and the overdose epidemic was declared a national emergency, there is increasing interest in field testing of illicit substances for law enforcement and harm reduction stakeholders. Street drugs consist of unregulated and highly variable mixtures of illicit drugs and cutting agents, including diluents and adulterants, making them difficult to evaluate under field conditions. Tools most commonly used for field drug analysis include presumptive drug test pouches containing concentrated liquid reagents, immunoassay-based test strips, liquid dropper reagents, portable Fourier transform infrared spectrometers and mass spectrometers. While effective, disadvantages of these technologies include financial limitations, safety concerns, and analytical impacts from the presence of cutting agents and multicomponent illicit drug mixtures on presumptive substance identifications in the field. These challenges have led to the need for and interest in a screening tool with the ability to characterize known illicit drugs, cutting agents, and provide chemical information about emerging drugs of abuse.During the course of my thesis research, I developed, validated, and optimized a paper-based analytical device for illicit drug detection (idPAD). The idPAD involves a library of 12 colorimetric tests that are run simultaneously, each detecting different chemical functional groups and materials found in illicit drugs, diluents, and adulterants. The visual results produced from the 12 tests form a color barcode which is "read" by comparison to standard images. The idPAD could have a real impact on field drug detection. This device is inexpensive, field- and user- friendly, and does not require any specialized instrumentation or electricity. While the idPAD is not a replacement for laboratory confirmatory testing, these paper test cards can be used for rapid screening of unknown substances for the presence and identification of illicit drugs, cutting agents, and potential emerging drugs of abuse.In addition to illicit drug research, I have worked with non-profit organizations and governmental regulatory agencies in low- and middle-income countries on the implementation of a paper analytical device for pharmaceutical quality control including performing trainings for stakeholders and developing training materials.