A biological sterilization indicator system (10, 10'), the system comprising: a biological sterilization indicator (100, 500, 600) comprising: a housing (102, 502, 602) including a first portion (104, 504, 604), and a second portion (106, 206, 306, 406, 506, 606) adapted to be coupled to the first portion, the second portion being movable with respect to the first portion, when coupled to the first portion, between a first position and a second position; a container containing a liquid and being dimensioned to be positioned in the housing, at least a portion of the container being frangible, the container positioned in at least the first portion of the housing, the container having a first state in which the container is intact when the second portion of the housing is in the first position, and a second state in which the container is fractured when the second portion of the housing is in the second position; and at least one signal-modulating feature (153, 253, 353, 453, 553, 653, 653') located on at least one of the first portion and the second portion of the housing, the at least one signal-modulating feature positioned to be detectable to indicate when the second portion of the housing is in the first position or the second position; and a reading apparatus (12, 12') comprising: a well dimensioned to receive at least a portion of the biological sterilization indicator; and a first sensor located adjacent the well and positioned to detect when the well is empty and to detect at least one signal-modulating feature of the biological sterilization indicator to determine the position of the second portion of the housing with respect to the first portion of the housing when the biological sterilization indicator is positioned in the well. a biological sterilization indicator (100, 500, 600) comprising: a housing (102, 502, 602) including a first portion (104, 504, 604), and a second portion (106, 206, 306, 406, 506, 606) adapted to be coupled to the first portion, the second portion being movable with respect to the first portion, when coupled to the first portion, between a first position and a second position; a container containing a liquid and being dimensioned to be positioned in the housing, at least a portion of the container being frangible, the container positioned in at least the first portion of the housing, the container having a first state in which the container is intact when the second portion of the housing is in the first position, and a second state in which the container is fractured when the second portion of the housing is in the second position; and at least one signal-modulating feature (153, 253, 353, 453, 553, 653, 653') located on at least one of the first portion and the second portion of the housing, the at least one signal-modulating feature positioned to be detectable to indicate when the second portion of the housing is in the first position or the second position; and a housing (102, 502, 602) including a first portion (104, 504, 604), and a second portion (106, 206, 306, 406, 506, 606) adapted to be coupled to the first portion, the second portion being movable with respect to the first portion, when coupled to the first portion, between a first position and a second position; a first portion (104, 504, 604), and a second portion (106, 206, 306, 406, 506, 606) adapted to be coupled to the first portion, the second portion being movable with respect to the first portion, when coupled to the first portion, between a first position and a second position; a container containing a liquid and being dimensioned to be positioned in the housing, at least a portion of the container being frangible, the container positioned in at least the first portion of the housing, the container having a first state in which the container is intact when the second portion of the housing is in the first position, and a second state in which the container is fractured when the second portion of the housing is in the second position; and at least one signal-modulating feature (153, 253, 353, 453, 553, 653, 653') located on at least one of the first portion and the second portion of the housing, the at least one signal-modulating feature positioned to be detectable to indicate when the second portion of the housing is in the first position or the second position; and a reading apparatus (12, 12') comprising: a well dimensioned to receive at least a portion of the biological sterilization indicator; and a first sensor located adjacent the well and positioned to detect when the well is empty and to detect at least one signal-modulating feature of the biological sterilization indicator to determine the position of the second portion of the housing with respect to the first portion of the housing when the biological sterilization indicator is positioned in the well. a well dimensioned to receive at least a portion of the biological sterilization indicator; and a first sensor located adjacent the well and positioned to detect when the well is empty and to detect at least one signal-modulating feature of the biological sterilization indicator to determine the position of the second portion of the housing with respect to the first portion of the housing when the biological sterilization indicator is positioned in the well.