The Angel phase describes a 300–400-year cultural manifestation of the Mississippian culture of the central portions of the United States of America, as defined in the discipline of archaeology. Angel phase archaeological sites date from c. 1050 - 1350 CE and are located on the northern and southern sides of the Ohio River in southern Indiana, such as National Historic Landmark Angel Mounds near present-day Evansville; northwestern Kentucky, with Wickliffe Mounds and the Tolu Site; and Kincaid Mounds State Historic Site in Illinois. Additional sites range from the mouth of Anderson River in Perry County, Indiana, west to the mouth of the Wabash in Posey County, Indiana.

One of the most extensive Mississippian artifact assemblages in its region, the Angel phase collection consists of well over 2.5 million individually catalogued objects. The count is rising yearly with continued excavation and research. Characteristic to Angel phase mounds in particular, the assemblage is overwhelmingly ceramic, with vessels and pottery fragments occupying just under 70% of the total count, or more than 1.8 million sherds. (Hilgeman, 2000:25). Of this vast quantity, 98% are plain or decorated with relatively common designs. The common decorations such as cord marking and fabric impressing are very rare.

Chipped-stone artifacts and debris are uncommon at Angel phase mounds, consisting of less than 1% of all artifacts. Ground-stone artifacts are fewer, representing about one-seventh the frequency of their chipped counterparts. Faunal remains are, however, a significant portion of the assemblage, with specimen counts attributing about 20%.

From a regional perspective, certain patterns and comparisons can be observed between other assemblages and among time periods. First, the simplicity or plainness of the Angel collection is similar to comparable assemblages from the Tennessee-Cumberland region. It is considered more plain than other Ohio-Mississippi confluence assemblages. Second, there is a trend toward greater plainness as time progresses. From early Angel 2 phase to late Angel 3 phase, the percentage of decorated sherds relative to all sherds declined from 3% to 0.6%. This trend is in line with regional trends in Tennessee-Cumberland and Western Kentucky assemblages that deemphasized painting as a mode of decoration from prior to 1200 CE compared to afterward.

The chronology of Angel pottery is based upon certain markers that occur in the assemblage. These markers are chosen because they either appear to follow a continuous change over time, which allows classification by seriation, or they are absent/present in a stratigraphic-level base at the time of maximum usage. Rim thickness and handle variation are markers that gradually shift in pottery styles over time. They can be associated with the general early period, with the loop handle shifting toward the strap handle later. The appearance of a Ramey Incised sherd demarcates an earlier period, and the appearance of a Parkin Punctuated sherd indicates a later period.

The context in which these artifact markers are found contributes to whether the chronology can be deemed viable and acceptable as a temporal scale. To ensure that this is true, a series of eliminations of questionable layers is conducted to create a sample that represents undisturbed archaeological stratigraphy.

In the lower Ohio River valley in Illinois, Kentucky, and Indiana, the Mississippian-culture towns of Kincaid, Wickliffe, Tolu, and Angel Mounds have been grouped together into a "Kincaid focus" set, due to similarities in pottery assemblages and site plans. Most striking are the comparisons between the Kincaid and Angel sites, which include analogous site plans, stylistic similarities in artifacts, and geographic proximity. These connections have led some experts to hypothesize that the builders and residents were of the same society.

The 300-400 year span in which these types of artifacts and sites are found is called the "Angel phase". It is broken up into three subphases: