Provided are methods and compositions useful for assessing the length of telomeres. The disclosed methods and compositions are amenable to performance as a high-throughput method to assess telomere length (TL) and TL constitution using genomic DNA. Also provided are methods for diagnosing a telomere-related condition or disease in a subject, assessing general health and/or aging of a subject, establishing a relationship between telomere constitution and cancer and/or aging-related disease, assessing exposure to harmful substances and/or stresses of a subject, assessing response to a drug or drugs treatment of a subject, assessing disease risk of a subject, and assessing clinical outcome of a subject who is suffering from a disease/diseases. The methods are useful in studies of individuals and populations.