A method for annealing a doped silica-titania glass body, comprising the steps: heating the glass body to at or above the crystal melting temperature of the glass body for 30 minutes or longer, the glass body comprising a silica-titania based glass composition containing titania at 7 to 14 wt.% and at least one additional dopant selected from the group consisting of F, B, and OH, the glass body having a strain point and an annealing point; cooling the glass body from at or above the crystal melting temperature to a temperature below the strain point, wherein the crystal melting temperature is the lowest temperature at which titania crystals within a doped silica-titania glass, doped silica-titania glass body or other doped silica-titania form will melt, dissolve or otherwise substantially disappear within the doped silica-titania glass, body or form after an exposure of about 30 minutes to this temperature; and annealing the glass body after the step for cooling the glass body, the annealing conducted from an upper annealing temperature set at least 50°C below a crystallization onset temperature of the glass body down to a lower annealing temperature at a cooling rate from 30°C/hour to 0.01°C/hour, wherein the crystallization onset temperature is the temperature at which a silica-titania glass that has been cooled at a rate of at least 100°C/hour from the crystal melting temperature to a temperature below the strain point of the glass and showing a concentration of titania crystals below 0.1 wt.% develops at least 0.1 wt.% titania crystals after an exposure at this temperature for about 6 hours in flowing dry air, wherein the glass body exhibits an expansivity slope of less than 1.3 ppb/K 2 at 20°C after the annealing step, wherein the step for cooling the glass body from at or above the crystal melting temperature to a temperature below the strain point further comprises: cooling the glass body from at or above the crystal melting temperature at a cooling rate of 100°C/hour or greater down to an upper intermediate temperature above 50°C below the annealing point; and cooling the glass body from the upper intermediate temperature down to a lower intermediate temperature from 20°C greater than the strain point to 250°C less than the strain point at a cooling rate of 20°C/hour to 30°C/hour. heating the glass body to at or above the crystal melting temperature of the glass body for 30 minutes or longer, the glass body comprising a silica-titania based glass composition containing titania at 7 to 14 wt.% and at least one additional dopant selected from the group consisting of F, B, and OH, the glass body having a strain point and an annealing point; cooling the glass body from at or above the crystal melting temperature to a temperature below the strain point, wherein the crystal melting temperature is the lowest temperature at which titania crystals within a doped silica-titania glass, doped silica-titania glass body or other doped silica-titania form will melt, dissolve or otherwise substantially disappear within the doped silica-titania glass, body or form after an exposure of about 30 minutes to this temperature; and annealing the glass body after the step for cooling the glass body, the annealing conducted from an upper annealing temperature set at least 50°C below a crystallization onset temperature of the glass body down to a lower annealing temperature at a cooling rate from 30°C/hour to 0.01°C/hour, wherein the crystallization onset temperature is the temperature at which a silica-titania glass that has been cooled at a rate of at least 100°C/hour from the crystal melting temperature to a temperature below the strain point of the glass and showing a concentration of titania crystals below 0.1 wt.% develops at least 0.1 wt.% titania crystals after an exposure at this temperature for about 6 hours in flowing dry air, cooling the glass body from at or above the crystal melting temperature at a cooling rate of 100°C/hour or greater down to an upper intermediate temperature above 50°C below the annealing point; and cooling the glass body from the upper intermediate temperature down to a lower intermediate temperature from 20°C greater than the strain point to 250°C less than the strain point at a cooling rate of 20°C/hour to 30°C/hour.