The characterization of soil physical properties is fundamental to a wide range of human activities including agriculture, waste disposal, and construction. This research advances penetrometer technology through the development and evaluation of three new miniature sensors that assess soil properties. The Profile Cone Penetrometer (PCP) used a 60-degree tip angle for the measurement of cone index (CI). Results from the PCP evaluation showed that the tool was useful for delineating the depth and thickness of soil horizons that varied in bulk density, moisture, texture, or structure. However, it was not possible to estimate any of these property values very well because only CI was being measured. A Soil Imaging Penetrometer (SIP) was developed that enabled the collection of real-time, in-situ soil images. The SIP was tested against twenty-four soil samples of varying Munsell color designations to determine its ability to correctly measure soil color. Results indicated that the SIP is capable of determining the soil color in a more repeatable and objective manner than human evaluation of the same soil. The Physical Property Penetrometer (PPP) also was developed to estimate texture from both a tip force and sleeve friction measurement capability. The results clearly showed that with useful accuracy, texture could be estimated from PPP readings in near real-time, and that texture could be related in a useful way to saturated hydraulic conductivity (Ks). Overall the research demonstrates the usefulness of advanced, miniature penetrometers for rapidly assessing soil property information.