Overview

This study will describe, estimate, and explore the effectiveness of community-centered safety models (CCSMs)-including co-response, alternative response, and community violence intervention modalities-implemented across U.S. municipalities to prevent community violence among youth and young adults (YYA). Specifically, the investigators will (1) describe CCSM implementation using implementation-science methods, (2) estimate CCSMs' impacts on community-violence outcomes using quasi-experimental methods, and (3) explore operational and contextual factors associated with stronger or weaker effects.

Eligibility

Inclusion Criteria for Jurisdiction/Sites:

1. Intervention modality clarity: A single, identifiable CCSM-Co-Response (CRM), Alternative Response (ARM), or Community Violence Intervention (CVI)-implemented at city/county level.
2. Documented launch date \& scope: Public or official documentation specifying program start date, catchment, operating hours, staffing, eligibility, and core activities.
3. Observation window: ≥24 months pre-implementation and ≥12 months post-implementation of outcome data (monthly preferred; annual acceptable for fatal outcomes).
4. Outcomes coverage: Availability of primary outcomes (fatal and nonfatal violent injury) and at least one secondary justice outcome at the jurisdiction level.
5. Data quality: Stable geographic boundaries, consistent reporting practices, and no catastrophic breaks that preclude credible counterfactual fit.
6. Donor comparability: Jurisdiction characteristics and data cadence compatible with a pooled augmented synthetic control design (i.e., can be matched to a synthetic control and included in permutation tests).

Exclusion Criteria:

1. Pilot-only or indeterminate programs: Short-lived pilots, ambiguous or multi-modality rollouts where treatment timing or content cannot be reliably defined.
2. Severe data discontinuity: Major boundary changes, reporting suspensions, coding overhauls, or dataset gaps that undermine time-series integrity (e.g., prolonged outages during system migration) and cannot be addressed with standard remedies.
3. Overlapping major interventions: Concurrent, poorly measured citywide initiatives (e.g., sweeping policy bundles) that coincide with the CCSM start and make identification infeasible.
4. Insufficient pre-period: \<24 months pre-implementation data for primary outcomes.
5. Incompatible cadence/aggregation: Outcomes only available at spatial or temporal units that cannot be aligned with other sites or donors.