The authors present the design and implementation of associate investigations of young children with positive tuberculin skin test results. Case study analysis of an associate investigation was done using epidemiologic surveillance techniques, medical interviewing, sociogram mapping, tuberculin skin testing, radiographic evidence, and bacteriologic analysis. Deoxyribonucleic acid fingerprinting of the Mycobacterium tuberculosis isolates using a standardized IS6110-based restriction fragment length polymorphism analysis and IS6110-independent DNA spoligotyping methods was done to track and identify specific bacterial strains. Deoxyribonucleic acid fingerprinting and spoligotyping done on isolates obtained from family members demonstrated same-strain transmission of M. tuberculosis. Three adults with active pulmonary disease and six individuals with latent tuberculosis (TB) were discovered during this investigation. The arrival of a family member from Mexico who had the same strain suggests that the source case lives in Mexico. A child with positive tuberculin skin test results indicates recent and potentially ongoing transmission of TB in the community. Targeted tuberculin skin testing performed on high-risk groups by primary care physicians allows for detection of TB infections. When TB infections are discovered in children, associate investigations can result in the discovery of undiagnosed adult cases and prevent further transmission within the community.