This year's (2010) forecast projects that current policies and procedures will result in a larger prison population in 10 years (n=10,409) than has been forecast by the two most recent estimates. This change is due to an upturn in prison admissions and a decline in releases, which has caused the inmate population to increase significantly since last February. The increase in prison admissions is more troubling than the decline in releases, since the reasons for increased admissions are unclear; whereas, the decline in the number of paroles is apparently related to new parole board members who are still adjusting to the board's role in controlling the size of the prison population. One factor that influences the anticipated increase in admissions continues to be 2005 legislation that pertains to sex offenders. This year's forecast projects the addition of 344 sex offenders to the prison population between June 30, 2010, and June 30, 2020. Nearly all of this increase is due to anticipated increases in admissions for violation of the "Special Sentence," which requires 10-year or lifetime supervision of most sex offenders following completion of their original periods of prison or probation. Data are also estimated for male and female inmates and prison capacity. Other factors discussed as influences on prison growth are decreases in felony charges disposed, changes in sentencing and parole eligibility, admissions of drug offenders, increases and decreases in paroles, increases in inmate average length of stay, changes in community-based offender populations, and housing Federal prisoners/detainees. Opportunities for policy change that may influence the size of the prison population are discussed. Appended statistical tables