The COVID-19 pandemic has altered mental health care delivery like no other event in modern history. The purpose of this study was to document the magnitude of that effect by examining (a) the amount of psychologists' telepsychology use before the COVID-19 pandemic, during the pandemic, and anticipated use after the pandemic; as well as (b) the demographic, training, policy, and clinical practice predictors of these changes. This study used a cross-sectional, national online design to recruit 2,619 licensed psychologists practicing in the United States. Prior to the COVID-19 pandemic, psychologists performed 7.07% of their clinical work with telepsychology, which increased 12-fold to 85.53% during the pandemic, with 67.32% of psychologists conducting all of their clinical work with telepsychology. Psychologists projected that they would perform 34.96% of their clinical work via telepsychology after the pandemic. Psychologists working in outpatient treatment facilities reported over a 26-fold increase in telepsychology use during the pandemic, while those in Veterans Affairs medical centers only reported a sevenfold increase. A larger increase in percentage telepsychology use occurred in women, in psychologists who reported an increase in telepsychology training and supportive organizational telepsychology policies, and in psychologists who treated relationship issues, anxiety, and women's issues. The lowest increases in percentage telepsychology use were reported by psychologists working in rural areas, treating antisocial personality disorder, performing testing and evaluation, and treating rehabilitation populations. Although there was a remarkable increase in telepsychology use during the COVID-19 pandemic, individual and practice characteristics affected psychologists' ability to adopt telepsychology. (PsycInfo Database Record (c) 2021 APA, all rights reserved).